Preheat your oven to 350 degrees F. Prepare three 8-inch or four 6-inch round cake pans by spraying each pan with non-stick spray, covering the bottom of each pan with parchment paper and spraying the parchment paper with non-stick spray as well. Set aside.

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

Turn the mixer to low speed and gradually add the dry ingredients and buttermilk alternately, starting and ending with the dry ingredients. Mix until incorporated, only about 20 seconds.  Scrape down the sides of the bowl and mix on low for another 10 to 20 seconds.

Let the cakes cool in the pans for 10 minutes and then invert onto wire racks to cool completely. 

Level each cake layer before assembly. If you're not using the layers right away, wrap each cake layer with plastic wrap and freeze.

In the bowl of a stand mixer, fitted with the paddle attachment, beat the butter on medium speed for about 2 minutes, until light and fluffy.

With the mixer on low speed, slowly add the powdered sugar, followed by the vanilla, butterscotch flavoring and heavy cream.

Continue to beat the frosting on medium-high speed for an additional 5 minutes, until the mixture has lightened in color and texture.

Before frosting your cake, make sure to use a wooden spoon to beat the frosting by hand to push out any air pockets.

In a small microwave safe bowl, heat the butterscotch sauce for about one minute. Pour the sauce over the butterscotch chips and allow to sit for a few minutes. Stir to combine.

I recommend making the marshmallow cream last, near the time you're serving the cake, so it's fresh and stays puffy.

In the bowl of a standing mixer, whisk the eggs and salt until fluffy and frothy.

Meanwhile, heat the sugar, corn syrup, water and vanilla paste. Heat over medium flame until the sugar is dissolved and just simmering, about 5 minutes.

With the mixer on medium speed, add a tiny bit of the hot sugar mixture to the egg whites at a time. (Temper the eggs - don't scramble the them)

Eventually, all of the sugar will be added and then turn the mixer up to high. Beat the mixture on high for about 5 minutes or until very stiff and shiny. 

Place your first cake layer, top side (leveled side) up, on a cake board. Spread about one cup of frosting on the cake layer, creating a little rim around the edges with your offset icing spatula. 

Pour about 1/4 cup of the drip/butterscotch caramel sauce on the frosting and spread evenly.

Place the next cake layer, also top side up, on the filling. Spread another cup of frosting on the cake layer, followed by more drip. 

Place the final cake layer, top side down, on the filling and coat the entire cake with a thin coat of frosting to lock in the crumbs. Remember, this coat of frosting does not need to look pretty, It's just a thin layer of frosting to hold the crumbs in. Freeze the cake for 10 minutes.

After the crumb coat is set, continue to frost the rest of the cake. 

Using a spoon, pour the remaining butterscotch caramel sauce over the edges of the cake. Top with the marshmallow cream and enjoy!

Cake can be frozen in an airtight container for up to a week. Serve at room temperature.