Prepare cake pans by lining the bottoms with parchment paper. You can use either three 8? cake pans, or three 9? cake pans. Preheat the oven to 350 degrees.

In a standing mixer, whisk butter and sugar until light and airy. Approximately 3-5 minutes, stopping at 2 minutes to scrap down the sides.

In a separate bowl, whisk together the egg, egg whites, sour cream, milk and vanilla.

In a third bowl, whisk together the GF flour, baking powder, baking soda, potato starch, guar gum and salt.

Set the mixer to medium/low speed, and alternate adding the wet and dry ingredients to the butter and sugar mixture, starting and ending with the wet ingredients.

Once combined, turn off the mixer. The batter will be smooth and thick.

Divide the batter evenly between the cake pans and use the angled icing spatula to smooth the batter into a flat layer.

Pop the cake pans into the oven and prep your frosting while you wait for these beauties to bake! Bake for 15 minutes, rotate, then bake another 15 minutes. When cakes are golden brown, and you can insert a toothpick into the middle with only crumbs sticking to it – they are ready!

Let cakes cool for 15 minutes before removing from the cake pans. Place the cakes on a cooling rack. They must be completely cool before adding frosting to the cakes.

Prepare the peach puree by peeling and pitting 3 ripe peaches. Place the peaches, brown sugar and vanilla in a sauce pan and cook until bubbly. Cool slightly, then blend in a blender or food processor until smooth.

For the crumble, whisk together the dry ingredients, then work in the butter with your fingers until the mixture forms small crumbles. Chill for 10 minutes, then bake on a parchment lined baking sheet for 15 minutes at 375 degrees. Stir the crumble with a spatula halfway through.

In a stand mixer, using a paddle attachment beat the butter and cream cheese until smooth.

Add the powdered sugar 1 cup at a time, beating in between each addition. Once the sugar is added, add vanilla to the mixer, then set it to medium speed and beat the frosting for 5 minutes until smooth, creamy and light.

To assemble, place the first cake layer top side up, in the center of the cake board. Spread buttercream atop, then pipe a rim of the buttercream around the edge of the cake and fill the center with a thin layer of peach puree, then sprinkle the crumble on top of the puree.

Place the second cake layer on top of the buttercream and filling, bottom side down. Repeat piping and filling.

Place final cake layer, top side down (flip it so the flat bottom is facing up).

Crumb coat the entire cake with a thin layer of the buttercream and pop it into the freezer for about 10 to 15 minutes to set this layer of frosting.

Once the crumb coat is set, continue to frost the cake with the remaining frosting. I like to use a cake edger or scraper, but you don’t have to use this. You can always create a rustic look with a spatula.

Decorate the top of the cake however your heart desires!