Easy, one bowl birthday cake for one's birthday. If they are so inclined to share, it should only be with 2 others, max.
mixer for batter
1stick unsalted butter113g
1/2teaspoonfine sea salt
2teaspoonsimitation vanilla or pure vanilla extractor a combination
1 1/2cupsorganic powdered sugar200g
1-2tablespoonsbuttermilkmilk, heavy cream, or sour cream
1 1/2tablespoonscoconut oil*see notes below for substitutions
1/4teaspoonfine sea salt
2large egg whites
3tablespoonsmini chocolate chips
Make the buttercream: in a small bowl, use a hand mixer to beat the butter with the salt and vanilla until light and fluffy, at least 3 minutes. Add the powdered sugar and beat to combine. Add 1 TB of the milk and if it doesn’t smooth out, add another TB. Set the buttercream in an airtight container until cake is ready to be assembled.
Preheat oven to 325 and butter and flour an 8×8″ square pan.
In a bowl, beat the butter, oil, salt and vanilla with the sugar until very light and fluffy, 3-5 minutes.
Add the egg whites one by one, allowing the first to fully incorporate before the second. Beat until very fluffy.
Add the cake flour, baking soda and powder and buttermilk all at once and beat to combine.
Fold in the sprinkles and chocolate chips, if using.
Pour into cake pan and bake for 30-35 minutes, until a cake tester comes out clean from the center.
When the cake is completely cool, use a ring to punch out four circles (this is easier to do if the cake has been frozen for a bit). You now have four tiny cake layers. Level them with a cake leveler or knife so they are the same height.
Stack the cake layers with buttercream. Between each layer you’ll want 1-2 tablespoons buttercream. Frost the sides.
If you don't have or don't want to use coconut oil and don't mind a yellowish tint to the cake, skip the coconut oil and use full eggs (including the yolks) for this recipe.