Preheat your oven to 350°F (175°C). In a large mixing bowl, whisk together the all-purpose flour, baking powder, baking soda, and salt until well combined.

In another bowl, cream the softened unsalted butter and granulated sugar with a hand mixer until light and fluffy, about 3-4 minutes.

Add in the large eggs one at a time, mixing thoroughly after each addition.

Incorporate the buttermilk and vanilla extract, followed by gradually folding in the dry ingredients along with the crushed toffee pieces and optional chopped pecans.

Divide the prepared batter evenly between two greased 9-inch round cake pans. Bake for 25-30 minutes, or until a toothpick comes out clean.

Allow the cakes to cool in the pans for about 10 minutes before transferring them to wire racks to cool completely.

To create the caramel sauce, combine granulated sugar and unsalted butter in a saucepan over medium heat until melted and golden.

Gradually whisk in the heavy cream and a pinch of salt, continuing to stir until the sauce thickens, about 3-5 minutes.

In a mixing bowl, beat together softened unsalted butter and powdered sugar until fluffy. Slowly drizzle in the cooled caramel sauce, vanilla extract, and heavy cream.

Once the cake layers have cooled, place one layer on a serving plate and spread a layer of frosting over the top, then place the second layer on top.

Frost the top and sides of the entire cake with remaining frosting and drizzle additional caramel sauce over the top.