Preheat your oven to 350F/180C.
In a medium bowl combine melted butter, brown sugar, maple syrup, eggs, vinegar, vanilla and salt and whisk until combined.
Add raisins and chopped walnuts.
Roll out the pastry to a ⅛" thickness and cut out rounds with a 4" pastry cutter or use a glass. (My glass was 3.5" in diameter)
Line muffin tin cups with pastry rounds.
Fill the muffin cups with the maple/nut mixture until ⅔ full.
Bake for 20-25 minutes until the custard is set and the pastry is golden.
Run a knife around the edges of the tarts as soon as you remove them from the oven to release them from the tin. Let them cool for 15 min in the tin before removing.
Melt white chocolate and drizzle over the butter tarts for a festive finish.