Preheat your oven to 350°F (180°C) and prepare your Bundt pan by greasing it thoroughly.
In a large mixing bowl, combine the all-purpose flour, sugar, baking powder, and baking soda.
In a stand mixer, cream together the softened butter and sugar until fluffy, then add eggs one at a time.
Gradually alternate adding the dry mixture and milk to the creamed butter mixture.
If adding crushed Heath bar, fold it into the batter now.
Pour the batter into the prepared Bundt pan, smoothing the top with a spatula.
Bake for 40-45 minutes, until a toothpick comes out clean.
Remove from the oven and cool in the pan for about 10 minutes.
Prepare the toffee sauce by melting butter and brown sugar together, then stir in heavy cream.
Drizzle the warm toffee sauce over each cooled Bundt.
