Preheat oven to 350 degrees F (175 degrees C). Grease a 9 inch pie plate.
In a medium bowl, cream together the 1/2 cup butter and the sugars until light and fluffy. Beat in the eggs one at a time, then stir in the vanilla.
In a separate bowl, sift together the flour, salt, and baking powder. Gradually stir the dry ingredients into the wet mixture until well blended.
Stir in the raisins, currants, mixed candied fruit, mixed nuts, and mixed dried fruit. Pour into the prepared pie plate, and bake for 40 minutes, or until a toothpick inserted into the center comes out clean.
Meanwhile, in a medium bowl, combine the melted butter, white sugar, and flour. Mix until crumbly. Sprinkle over the pie when it is done baking.
Cool on a wire rack before serving.
Interesting Facts
Mince pies were traditionally served on Christmas Eve in the UK.
The filling is traditionally made with suet, sugar, spices, and dried fruits.
The crumbly topping is a modern twist on the traditional mince pie recipe.