No-Bake Chocolate Peanut Butter Bars

2 cups peanut butter, divided
3/4 cup (1 1/2 sticks) butter, softened
2 cups powdered sugar, divided
3 cups graham cracker crumbs
2 cups Semi sweet choc. chips

Grease 13x9 pan

Beat 1 1/4 cups peanut butter and butter in large mixer bowl until creamy. Gradually beat in 1 cup powdered sugar. With hands or wooden spoon, work in remaining powdered sugar, graham crackers crumbs, and 1/2 cup choc. chips. Press evenly into prepared pan. Smooth top with spatula.

Melt remaining peanut butter and remaining choc. chips in medium heavy duty saucepan over lowest possible heat, stirring constantly, until smooth. Spread over graham cracker crust in pan. Refrigerate for at least 1 hour or until choc. is firm.