Make the cake mix according to the box directions and pour into a sprayed 9x13 pan. Bake at 350 for 25-30 minutes, or until the center is no longer jiggly. Remove from the oven and immediately poke several holes with a fork or knife all over the top of the cake.
Microwave the caramel topping jar for 30 seconds and stir. Drizzle the caramel over the cake while it's still warm. Put some saran wrap over the cake and place in the fridge until cooled. When ready to serve, whip the whipping cream in a mixing bowl with an electric mixer until airy and stiff peaks. Add the powdered sugar to the whipping cream and beat another few seconds.
Spread the whipped cream over the top of the cake. Top the cake with a bag of chopped toffee bits with chocolate (Heath Bits) and chopped pecans. Serve cold.