How to Make the Cake:

• Step 1: Preheat the Oven. Start by preheating your oven to 350°F (175°C). This ensures the cake bakes evenly.
• Step 2: Prepare the Pan. Grease a 9x13 inch sheet pan with butter or line it with parchment paper for easy removal.
• Step 3: Cream Butter and Sugar. In a large mixing bowl, beat together the softened butter and sugar until light and fluffy. This should take about 3-5 minutes with an electric mixer.
• Step 4: Add Eggs and Vanilla. Add the eggs, egg yolks, and vanilla extract to the butter mixture. Continue mixing until everything is well combined.
• Step 5: Combine Dry Ingredients. In a separate bowl, whisk together the flour, baking powder, and salt. This will ensure even distribution of the leavening agents.
• Step 6: Alternate Mixing Dry Ingredients and Buttermilk. Gradually add the dry ingredients to the wet mixture, alternating with the buttermilk. Start and end with the flour mixture, mixing until just combined.
• Step 7: Bake the Cake. Pour the batter into the prepared sheet pan, smoothing the top with a spatula. Bake in the preheated oven for 25-30 minutes or until a toothpick inserted in the center comes out clean.
• Step 8: Make the Caramel Icing. While the cake is baking, prepare the caramel icing. In a saucepan, melt 6 tablespoons of butter over medium heat. Stir in the brown sugar and milk, bringing it to a gentle boil. Remove from heat and gradually whisk in the powdered sugar until smooth.
• Step 9: Cool and Ice the Cake. Once the cake is baked, allow it to cool in the pan for about 10 minutes before transferring it to a cooling rack. Let it cool completely before pouring the caramel icing over the top.
• Step 10: Serve and Enjoy. Slice into squares and serve. Enjoy the delightful combination of moist cake and rich caramel icing!