Place muffin cases in a 12-hole muffin tin and pre-heat the oven to 170°C.
Place the milk, sugar, olive oil, eggs and lemon zest into a large bowl and beat together until smooth.
In a separate bowl whisk together the sweet rice flour, oat flour, almond flour, poppy seeds, baking powder and salt until thoroughly combined.
Add the flour mixture to the wet ingredients and beat together until smooth.
Divide the batter into muffin cases, filling to just below the top.
Place the muffin tin into the oven and bake for about 20 minutes.
As soon as the muffin tin has been taken out of the oven, then lift out the muffins and leave on a cooling rack to cool completely before drenching with icing.
Make the icing by beating together the lemon juice and zest with the icing sugar until the icing is just pourable.
Spoon the icing over each muffin then leave to set.