Place sugar and water into a medium pot, stir to combine, but do not stir from this point forward. Cook over med-high heat, washing down the sides of the pot with a pastry brush dipped in water as needed to prevent crystals. If you have difficulties with crystallization or the bottom caramelizing faster, try using a larger pot/saucepan so the sugar mixture isn't so deep.

Cook until desired color of caramel is reached (amber) and immediately remove from heat. Very slowly pour in (room temperature) heavy cream while whisking quickly. The mixture will bubble up (a lot) and boil. Add (room temperature) butter, return to heat, and bring back to a boil. Simmer for 2 minutes whisking constantly.

Remove from heat and let cool to room temperature (about 2 hours). Transfer to a container and place in fridge to thicken.

Preheat oven to 350 F. Grease and flour three 6" cake rounds, line with parchment.

In a medium bowl, combine flour, baking powder, and salt. Set aside.

In the bowl of a stand mixer combine butter and sugar. Beat on med-high until pale and fluffy (2-3 mins). Add eggs one at a time, fully incorporating after each addition. Add vanilla and caramel and mix until incorporated.

Alternate adding flour mixture and milk, beginning and ending with flour (3 additions of flour and 2 of milk). Fully incorporating after each addition.

Spread batter evenly into prepared pans and bake for 35-40 mins or until a toothpick inserted into the center comes out mostly clean.

Place cakes on wire rack to cool for 10 mins then turn out onto wire rack to cool completely.

In a large saucepan, brown the 2 C of butter used in the frosting. Be careful not to burn the butter. Once browned, place in a container and cool/refrigerate until needed. Must be at least room temperature or slightly cooler to incorporate into frosting.

Place egg whites and sugar into a glass bowl, whisk until combined.

Place bowl over a pot with 1-2" of simmering water and whisk constantly until the mixture is hot and no longer grainy to the touch or reads 160F on a thermometer.

Move contents into your stand mixer and whip on med-high until the meringue is stiff and cooled (the bowl is no longer warm to the touch (approx. 5-10mins)).

Switch to paddle attachment. Slowly add butter and mix until smooth.

Add cooled caramel and whip until smooth.