Cheesy Brussel Sprout and Leek Gratin

This Brussel Sprout Gratin is cheesy, creamy, bubbling and golden. Shredded brussels are gently cooked in butter with finely cut leeks. An incredibly easy cheese sauce made from whole milk, cornflour, cheddar and cream cheese devours the vegetables. Plus this side dish is naturally gluten-free but oh so rich and delicious.

Brussel Sprout and Leek Gratin in a cast iron pan on wooden board

This year I made the smart decision to combine two of our traditional Christmas side dishes into one and I am flabbergasted that I have never done it before.

Cheesy Leek Gratin is a staple for our Sunday lunches but the addition of shredded brussel sprouts is such a festive revelation that I can no longer envisage a Christmas without this side dish on our table.

There would be uproar if I were not to serve out both a cheesy gratin and brussel sprouts on Christmas Day. We do have a few brussel sprout hold outs in the family but combined with buttered leeks in this rich creamy cheese sauce this dish will definitely encourage a few converts.

brussel sprouts in a colander next to leeks

Why is Brussel Sprout Gratin such a brilliant side dish?

  • Leeks and brussel sprouts are a vegetable marriage to last the ages.
  • It’s a brussel sprout dish to convert the most adamant haters.
  • It only take 25 minutes and is completely foolproof. No lumpy sauces here.
  • Gluten-free.
  • The perfect side dish which is delicious enough to be the main event for the vegetarians at the table.
  • The cheese sauce is easy to make, rich with both mature cheddar cheese and cream cheese.
  • Full of flavour thanks to smart seasoning.
  • Honey dijon mustard. It adds incredible depth to the sauce.
  • That final grilling means crunchy golden breadcrumbs and bubbling cheese – a tempting sight to add to the table.
  • Easy to make-ahead or freeze.

Shredded brussel sprouts and leeks in a pan

What ingredients do you need for this Brussel Sprout Gratin?

  • Brussel Sprouts – wash, trim the stalk and peel off any grubby layers before shredding.
  • Leeks – wash, trim the ends and slice into thin coins to prepare.
  • Butter – use unsalted so you can control the salt content.
  • Whole Milk – using whole milk means the sauce is very creamy.
  • Cornflour – makes the sauce lovely thick and smooth.
  • Mature Cheddar Cheese – I love a sharp mature cheddar but you can sub for any melting cheese you fancy. Red leicester or gruyere are also lovely choices.
  • Cream Cheese – I always use Philadelphia. It adds lovely richness to the sauce
  • Honey Dijon Mustard – the sweetness of this mustard makes all the difference.

  • Seasoning – onion granules, garlic powder, salt and pepper add lovely depth
  • Breadcrumbs – I use Mrs Crimbles Gluten-Free Breadcrumbs which are lovely and crunchy plus free of xanthan gum.


Close up of Brussel Sprout and Leek Gratin in a saucepan

How do you make Brussel Sprout and Leek Gratin?

  1. Cook the shredded Brussels and leeks in butter on a gentle heat for 15 minutes. Remove from the heat whilst you prepare the sauce.Brussel sprouts and leeks cooking in a pan
  2. Whisk the cornflour with the milk in a saucepan, then turn on the heat and whisk until bubbling and thick.
  3. Add the cheddar, cream cheese, mustard and seasoning and stir until the sauce is thick and smooth.preparing cheese sauce in a saucepancheese sauce in a saucepan
  4. Pour the sauce over the vegetables and mix until thoroughly combined.Cheese sauce being poured over brussel sprouts and leeks
  5. Transfer the cheesy sprouts and leeks to an oven-to-table dish and sprinkle over the breadcrumbs and extra cheese.Brussel Sprout and Leek Gratin ready to go into the oven
  6. Grill until golden and bubbling.Brussel Sprout and Leek Gratin in a cast iron pan on wooden board

Pro Tips

  • Peel off the outer layer of the Brussels and trim off the stalks to prepare.
  • Shred the brussels and leeks as thin as you can for beautiful ribbony vegetables.
  • You want the Brussels and leeks to be wilted in the butter but just turning golden at the edges.
  • Swap out mature cheddar cheese for red leicester for a beautiful festive colour.
  • If you can’t get hold of honey dijon mustard then regular dijon will do.

Recommended Equipment to make Cheesy Brussel Sprout and Leek Gratin

  • Cheese Grater – I have a few Microplane graters but my favourite for grating cheddar is this course grater. It’s grates quickly and is so easy to wield.
  • Whisk – In a similar vein I have a lot of different whisks but my favourite for sauces in this Flexi Whisk which gets into all the nooks and crannies of the saucepan meaning you get no unnecessary lumps.
  • Oven-to-Table Pan – I wouldn’t necessarily  but for our weekly Sunday lunches you can bet I make and serve my gratins in my favourite cast iron pan. It’s large enough that the pan can accommodate one-pan meals and small enough that it can fit into most ovens. Plus it looks pretty good on the table as part of a homestyle meal.

Make Ahead – This dish is so easy to prepare in advance. I usually get it to the stage before the final grill. Keep in an airtight container in the fridge for up to 3 days. Transfer the gratin to an oven-to-table dish and sprinkle over the breadcrumbs and extra cheese.

However, at this point heat the dish in the oven instead of the grill to ensure the dish is piping hot. Cook at 180°C for 20 minutes until golden and bubbling.

Freeze – You can freeze any leftovers no problem. However, you can also make the dish ahead of time as above. But instead of storing in the fridge you can freeze for up to 2 months. Defrost completely before cooking in the oven.

Close up of Brussel Sprout and Leek Gratin in a saucepan

Variations of Brussel Sprout and Leek Gratin

  • Add cooked and chopped streaky bacon into the gratin before the final grill.
  • Sub in some blue cheese into the sauce for a lovely complex dish.
  • Include shredded kale into the proceedings.

Try these recipes if you are looking for more delicious side dishes

Gluten-Free Cauliflower Cheese
Carrot and Swede Mash
Braised Red Cabbage
Cream Baked Roast Potatoes
Duck Fat Roasted Parsnips
Chestnut and Sage Stuffing
Gluten-Free Yorkshire Puddings
Gluten-Free Gravy

If you make Brussel Sprout and Leek Gratin then please leave a comment below and/or give the recipe a rating. If you then go on to use this recipe as a launch pad for your own leftover creation then I’d also love it if you’d share it and tag me on Instagram. It is so lovely for me to see your versions and variations of my recipes.

Cheesy Brussel Sprout and Leek Gratin

Brussel Sprout and Leek Gratin is cheesy, creamy, bubbling and golden. Shredded brussels are gently cooked in butter with finely cut leeks. An incredibly easy cheese sauce made from whole
milk, cornflour, cheddar and cream cheese devours the vegetables. Plus this side dish is naturally gluten-free but oh so rich and delicious.
Prep Time5 mins
Cook Time25 mins
Course: Side Dish
Cuisine: British
Servings: 8 people
Calories: 290kcal

Ingredients

  • 2 tablespoons unsalted butter
  • 750 g brussel sprouts bottom stem removed then shredded
  • 2 leeks washed, topped and tailed and sliced into thin rounds
  • ¼ teaspoon salt
  • 500 ml whole milk
  • 4 tablespoons cornflour
  • 150 g mature cheddar cheese + 50g extra to sprinkle
  • 150 g cream cheese
  • 2 teaspoons honey dijon mustard
  • 1 teaspoon onion granules
  • 1 teaspoon garlic powder
  • ¼ teaspoon salt
  • ¼ teaspoon ground black pepper
  • 2 tablespoons gluten-free breadcrumbs

Instructions

  • Melt the butter in a large wide bottomed saucepan then add the shredded brussel sprouts and leeks with the salt.
  • Cook the brussel sprouts and leeks for 10-15 minutes on a gentle-medium heat stirring occasionally. The leaves should be wilted and just starting to turn golden at the edges.
  • Remove from heat and set aside whilst you prepare the cheese sauce.
  • Whisk together the milk and cornflour in a large saucepan until smooth. Then turn on the heat and bring up to a gentle boil, whisking all the time. As soon as the sauce begins to boil then the mixture will begin to thicken.
  • Add the cheddar cheese, cream cheese, Dijon mustard, onion granules, garlic powder and salt and stir in until the sauce is thick and smooth. Once the sauce just beings to bubble then remove from the heat.
  • Pour the sauce over the brussel sprouts and leeks and mix together until fully combined. Transfer to an oven-to-table dish and sprinkle over the breadcrumbs and extra cheddar cheese.
  • Place the dish under a grill on medium-heat for 5-10 minutes until the breadcrumbs are golden and the cheese is bubbling.
  • Serve straightaway.

Notes

  • Serves 6-8 people as a side dish
  • Peel off the outer layer of the Brussels and trim off the stalks to prepare.
  • Shred the brussels and leeks as thin as you can for beautiful ribbony vegetables.
    You want the Brussels and leeks to be wilted in the butter but just turning golden at the edges.
  • Swap out mature cheddar cheese for any melting cheese you like. Festive coloured Red Leicester or nutty gruyere are lovely choices.
  • If you can’t get hold of honey dijon mustard then regular dijon will do.
  • Before the final grill transfer into an ovenware dish you would be proud to serve at your table.
  • Make ahead – prepare the dish up the final grilling stage. Keep in an airtight container in the fridge for up to 3 days then transfer to an oven-to-table dish, sprinkle on the breadcrumbs and cheese. But do cook in the oven for 20 minutes at 180°C to ensure the dish is piping hot.
  • Freeze – You can freeze the finished dish or the gratin up to the final grilling stage. Defrost completely then re-heat according to the advice above.

Nutrition

Calories: 290kcal | Carbohydrates: 23g | Protein: 12g | Fat: 18g | Saturated Fat: 11g | Cholesterol: 54mg | Sodium: 384mg | Potassium: 536mg | Fiber: 4g | Sugar: 7g | Vitamin A: 1706IU | Vitamin C: 82mg | Calcium: 277mg | Iron: 2mg