Irresistable Bars-Butter Tart Squares

This recipe is so delicious, I really have to limit myself on how many I eat. So YUMMY! Here's the recipe:
Butter Tart Bars:
Base:

2 cups flour
1 cup butter
1/2 cup granulated sugar
Combine flour and sugar, then with a pastry blender cut in butter until crumbly. Press into a 10X15 cookie/bar sheet. Bake for 15 minutes at 350 degrees.

Topping Ingredients:
1/2 cup butter, softened------ 2 cups brown sugar
4 eggs --------------------------4 tablespoons flour
1 teaspoon baking powder---- 1 teaspoon vanilla
pinch of salt --------------------1 1/2 cups raisins
3/4 cup coarsely chopped pecans
( I used 1/2 cup pecans and 1/4 cup walnuts because
I didn't have enough pecans, and it was still very flavorful)

Mix together butter and sugar, then blend in the eggs. Add flour, baking powder, salt and vanilla. Stir in raisins and pecans. Pour over the base. Bake at 350 degrees for 20 to 25 minutes or until top springs back when lightly touched. Cool, cut into squares. Freezes well.