Homemade Twix Bars

I got this recipe from my friend Janie.  She said that she makes this recipe when she has a left-over cake mix that she doesn't know what to do with.  These bar cookies are really delicious but certainly not low cal.  We didn't want to overdo it so I sent a container full with my husband to work to share with his co-workers.

HOMEMADE TWIX BARS

1 pkg. (18 – ¼ oz.) yellow cake mix

½ c butter or margarine
1 egg
½ c peanut butter chips
½ c chocolate chips
2 T cornstarch
1 jar (12-oz.) caramel ice cream topping
¼ c peanut butter
1 can (16-oz.) chocolate frosting

In a mixing bowl, combine the dry cake mix, butter and egg; beat until no longer crumbly, about 3 minutes. Stir in all chips. Press into a greased 13x9-inch baking pan. Bake at 350º for 18-22 minutes or until lightly brown.

Meanwhile, in a saucepan, combine cornstarch, caramel topping and peanut butter until smooth. Cook over low heat, stirring occasionally, until mixture comes to a boil, about 15 minutes. Cook and stir 1-2 minutes longer. Remove from heat. Spread evenly over warm crust. Bake 6-7 minutes longer until almost set. Cool completely on a wire rack.

Spread with frosting. Refrigerate for at least 1 hour before cutting.  Store in refrigerator.