1/2 c. brown sugar
1 c. peanut butter, divided
1/4 c. butter, softened
1 c. flour
1 (8 oz.) pkg. cream cheese
1/2 c. sugar
1 tsp. vanilla
2 eggs
2 c. Cool Whip
1 c. chocolate chips

Combine brown sugar, butter, flour and 1/2 cup peanut butter. Sprinkle into an ungreased 9"x13" pan, saving 1 cup of crumb mix for topping. Combine cream cheese, sugar, remaining peanut butter and vanilla. Beat at medium speed until smooth. Add eggs, one at a time. Fold in Cool Whip and spoon mix over crust. Melt chocolate chips and drizzle over creamed mix. Cut through to marble. Press reserve crumbs over top and press in slightly. Freeze at least 2 hours. Remove from freezer 15 minutes before serving.