Chewy Caramel Squares

1 cup (2 sticks) butter
1 cup light brown sugar
1 cup dark brown sugar
2 eggs, beaten
2 cups flour
2 teaspoons baking powder
2 teaspoons vanilla extract
2 cups chopped pecans
confectioners' sugar (optional)

Heat oven to 325 degrees F.

Melt butter in a large glass bowl in the microwave. Let cool slightly. Add brown sugar and stir well. Add eggs, flour, baking powder, vanilla extract and pecans. Mix well. Spread in a greased 13 x 9-inch pan and bake for 30 minutes. Allow to cool, then cut into squares. Sprinkle with confectioners' sugar if desired.