To begin with make your pastry. Take the butter out of the fridge and slice very finely with a sharp knife, then place in a large mixing bowl with the flour.
Tear the butter up and coat thoroughly with the flour, then begin to rub gently between your fingertips until you reach very rough breadcrumbs, don’t take it too fine. It should take less than 5 minutes.
Add the sugar, salt, egg and egg yolk then bring together into a dough. Tip it out onto the work surface and press together to form a ball. Wrap in baking parchment and chill in the fridge for 30 minutes.
Meanwhile make the filling. Warm the syrup and black treacle with the salt, then tip into a large mixing bowl.
Whisk in the double cream, then the egg.
Add the breadcrumbs and the pecans, lemon juice and vanilla then set aside.
Pre-heat the oven to 170°C.
Remove the pastry from the fridge and roll out until it is about 3mm thick. Line the pastry into the bottom of the tin. The tin I used was 35cm x 11cm.
Place some greaseproof paper on top of the pastry then pour baking beans on top.
Place in the oven for 15 minutes to blind bake. Remove the baking beans, brush with the egg wash then place back in the oven for a further 5 minutes.
Turn the oven down to 160°C.
Stir the treacle mixture, then pour into the pastry. Place in the oven and bake for 35-40 minutes until the filling has set. Allow the tart to cool in the tin before cutting.