Preheat the oven to 350°F (175°C). Grease and flour a 9x13-inch baking pan or two 9-inch round cake pans.
Prepare the batter: In a large mixing bowl, beat the sugar, eggs, and vegetable oil until smooth and creamy. Add vanilla extract and sour cream, mixing until fully combined.
Mix dry ingredients: In a separate bowl, whisk together the flour, baking powder, baking soda, and salt.
Combine wet and dry ingredients: Gradually add the dry ingredients to the wet mixture, stirring gently until just combined. Fold in the SKOR or Heath Bar bits.
Bake: Pour the batter into the prepared pan(s) and bake for 30–35 minutes, or until a toothpick inserted in the center comes out clean. Let the cake cool completely before frosting.
Make the frosting: In a large bowl, beat together the vegetable shortening and margarine until light and fluffy. Slowly mix in the icing sugar, vanilla extract, and milk until smooth.
Frost the cake: Spread the frosting evenly over the cooled cake and sprinkle with additional toffee bits for garnish.
Serve and enjoy!