In a medium-size sauce pan, combine the sugar, cola, and butter over medium heat. Stir until the mixture is smooth and the sugar has dissolved completely.

While stirring the cola mixture vigorously (so your eggs don't scramble), gradually add the eggs, one at a time.

With your mixer on low speed, gradually add the wet ingredients to the dry ingredients. Combine until no streaks of the dry mixture remain, about 30 seconds. Scrape down the sides and bottom of the bowl and stir again for about 10 to 20 seconds. Do not over-mix your batter. Over-mixing your batter will cause it to sink when it's baking.

Let the cake layers cool on racks for 10 minutes before inverting onto greased wire racks. Gently turn the cakes back up so the tops are up and cool completely.

Once the cakes are cooled completely, level the tops slightly to allow the glaze to soak into the cake.

Wrap each cake layer with plastic wrap and chill in freezer for at least an hour before using. The cake layers can be stored for up to a few days wrapped once in plastic wrap and frozen. To store longer than a few days, wrap twice in plastic wrap, then in foil, and seal in a zip-lock bag.

Take the cake layers out of the fridge about an hour prior to assembly. You can wait to add the glaze to the layers until they've thawed a bit.

In a medium-size saucepan, over medium heat, combine the butter, cola and cocoa powder. Stir until well-combined.

Take the mixture off the heat and combine with the powdered sugar. Mix until no clumps remain.

This will be a thinner consistency than buttercream. I think it's best to make this ahead of time so it has a little time to thicken. Store in an air-tight container in the refrigerator.

In the bowl of a stand mixer fitted with a paddle attachment, cream the butter for about 2 minutes. This will soften the butter without it having to be warm.

With the mixer on low speed, gradually add the sifted powdered sugar, one cup at a time, mixing a little in between each addition.

With mixer on medium speed, add whipping cream, vanilla and salt.

Turn the mixer to medium-high speed and beat for an additional 5 to 7 minutes. The frosting will become lighter in color and texture.

Before spreading on your cake, spend a couple minutes mixing the buttercream by hand with a wooden spoon to push out the air pockets.

Place the first cake layer, top side up on a cake plate or cake board set on a turn table.

Pipe a rim of the buttercream around the edge of the cake.

Pour about 1/2 cup of the glaze on the cake, spreading evenly.

Place the second cake layer on top of the filling and repeat steps 2 and 3.

The final cake layer will go top-side down on the filling.

Apply a thin coat of frosting around the entire cake to lock in the crumbs. Freeze for about 10 minutes.

After the crumb coat is set, continue frosting and decorating the cake.

Note: To make the ombre effect on the cake, take about 1 1/2 cups of the buttercream and combine with about 3 tablespoons of the glaze.