1/2 c. crunchy peanut butter
1/3 c. softened butter
3/4 c. brown sugar, packed
3/4 c. sugar

Combine in large bowl. Beat until creamy. Gradually beat in 2 eggs and 2 teaspoons vanilla.

In small bowl, combine:

1 c. flour
1 tsp. baking powder
1/4 tsp. salt

Blend in peanut butter mixture. Spread in greased baking pan. Sprinkle 1 package chocolate chips over surface until slightly melted, then swirl. Bake at 350 degrees for 5 minutes. Return to oven for 30 minutes. Cool and cut.