1 white or yellow moist supreme cake mix
1 1/4 cups water
1/2 cup vegetable oil
6 tbsps all-purpose flour
1 cup milk
1 cup sugar
1 cup butter, softened
1 cup creamy peanut butter
1 tsp vanilla
3/4 cup semisweet chocolate morsels
1 tbsp vegetable oil
1/3 cup unsalted roasted peanuts, chopped
Preheat oven to 350 degrees. Generously grease and lightly flour two 9-inch cake pans. Set aside.
In a large mixing bowl at low speed, mix cake mix,water, oil, and eggs until moistened. Beat for 2 minutes at high speed. Pour batter into the prepared pans. Bake at 350 degrees for 25 to 35 minutes until a wooden toothpick inserted in the center of cakes comes out clean. Cool in the pans on a wire rack for 10 minutes. Remove the cakes from pans and allow to cool completely on wire racks.
While the cake is baking, prepare the filling. In a medium saucepan, combine the flour and milk. Cook the mixture over medium heat, stirring constantly, until very thick. Transfer the mixture to a bowl and cover with plastic wrap. Cool in the refrigerator while cake is baking and cooling. Combine the sugar, butter, peanut butter and vanilla in a large mixing bowl and cream together well. When the milk mixture is chilled, add to the creamed mixture and beat until fluffy, about 2 minutes.
Cut the cooled cake layers in half horizontally using a thread or a long sharp knife to form 4 thin layers. Place one layer on the serving plate with the cut side up. Spread 1/3 of the filling mixture evenly over the layer. Repeat with the second and third layers. Top with the remaining layer putting it cut side down.
In a small microwave-safe bowl, combine the chocolate chips and oil. Microwave on medium for 1 to 2 minutes until chocolate morsels are melted. Stir until smooth. Reserve 1/4 cup of the glaze. Spread remainder of the glaze evenly over the top of the cake. Sprinkle with the chopped peanuts. Use the reserved glaze to drizzle over the peanuts and down sides of the cake. Refrigerate until serving time. This cake should be refrigerated at least 2 hours before cutting. Refrigerate any leftovers.