Chocolate Toffee Caramel Cake

Ingredients

• 1 1/3 cups butter, softened and divided
• 1 cup sugar
• 1 cup firmly packed dark brown sugar
• 1 tsp vanilla extract
• 6 large eggs
• 1 1/2 cups all-purpose flour
• 1 tsp baking powder
• 1 tsp baking soda
• 1/4 tsp salt
• 1 cup sour cream
• 2 cups firmly packed light brown sugar
• 2/3 cup evaporated milk
• 1 recipe Caramel Cream Cheese Frosting (recipe follows)
• Garnish: chopped English toffee-flavored candy bars