In a food processor add the flour, sugar, salt and baking powder. Pulse until all mixed.
Add the butter and Crisco then pulse until mixture looks like crumbly cornmeal.
Add egg, milk and vanilla and mix until dough starts to form a ball.
Turn out dough onto a board and lightly work dough until its smooth.
Divide dough into two flattened rounds, cover with plastic wrap and refrigerate for 1 hour.
Starting with the first piece of dough, place it onto a floured board. Roll it out to 1/4" thick.
Using a 3 inch pastry cutter or glass, cut out 12 rounds.
Place each round into the mould and press into mould to remove all air.
Add about 2 tablespoons of the custard to each of the moulds.
Cover each with a 3" round of dough. Let chill in the refrigerator for an hour or overnight. Brush tops with egg wash, then bake at 425° for 15 -18 minutes.