In a medium bowl or measuring cup, combine and stir the egg whites, whole egg and the clear vanilla. Set aside.

In another small bowl or measuring cup, combine the peach yogurt and peach nectar. Stir to combine. Set aside.

In a bowl of an electric mixer, fitted with a paddle attachment, combine the dry ingredients together on low speed for 30 seconds.

Add the butter one piece at a time, about every 10 seconds. Once all the butter is added, pour in the peach yogurt and peach nectar mixture and mix on low for about 1 minute, until the ingredients are incorporated.

Scrape down the sides of bowl and begin to add the egg mixture in 3 separate batches, mixing on medium-low until light and fluffy, about another minute. Fold once or twice to ensure the batter at the bottom of the bowl is incorporated and mix for another 20 to 30 seconds.

Bake until a cake tester or toothpick comes out with a few crumbs when inserted into the center, about 18 to 20 minutes (mine only took 18 minutes). Check cake at 18 minutes and then set the timer for 2 to 3 minute intervals if the cake needs to bake longer. You're looking for a few moist crumbs to come out on the toothpick when inserted into the center of the cake. Over baking your cake will dry it out.

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 if needed.

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.

In a medium saucepan, combine the peaches and sugar. Cook over medium heat, stirring occasionally, until the peaches are soft and the juices start to boil.

Remove from the heat and puree in a blender until smooth. 

Return the puree to the saucepan and add the sifted cornstarch. Cook on low until mixture thickens. Cool completely before using in the cake.

I recommend making the compote a day or two before you assemble the cake. The compote can be stored in an airtight container in the refrigerator for up to a week or in the freezer for a month.

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. 

Combine 2 cups of the vanilla buttercream with peach compote or peach preserves. Stir until combined.

Place the first cake layer, top side up (crumb side up), on a cake board or cake plate. Using an offset icing spatula, spread about a cup of the peaches and cream filling over the cake layer.

Pipe a rim of the vanilla buttercream around the edge of the cake. This will help support the cake layers and prevent the peach filling from spilling out. 

Spread about 1/4 cup of the peach filling on the cake layer. You don't want to add too much or your cake will be unstable as you stack and decorate. Reserve any left over compote to serve with the cake later.

Gently place the second cake layer on top of the filling and repeat steps 2 to 3.

Place the final cake layer top side down on the second layer of filling. 

Freeze the cake for about 10 minutes to help set the frosting and filling, making it a bit more stable for when you frost. If the cake still feels wobbly, add a dowel to the center of the cake (or you can even use drinking straws for this).

After the filling is set, use a small amount of vanilla buttercream and apply a crumb coat around the entire cake. Freeze the cake again for another 10 minutes to set the crumb coat.

After the crumbs are locked in, continue to frost and decorate the cake with the remaining vanilla buttercream.

To achieve a peach color, I used "orange" and "soft pink" Americolor food gels.