Vanilla Cake with Chocolate Frosting

Preheat the oven to 350℉ / 178℃
grease and line an 8x8 baking pan with parchment paper and set aside
In a medium bowl, combine the flour, baking soda, baking powder, and salt and whisk until combined.
1¼ cups (150 g) all purpose flour, ¾ teaspoon (3 g) baking powder, ¼ teaspoon (1 g) baking soda, ¼ teaspoon (1.5 g) salt
In the bowl of a stand mixer fitted with a paddle attachment (you could also use a hand mixer), cream together the butter and sugar until smooth, light in color, about 3 minutes. Then add the oil and mix for 30 seconds. Add in the egg + egg white, and vanilla extract, and beat well until completely combined.
6 tablespoon (84 g) unsalted butter, ⅔ cup (133 g) granulated sugar, 2 tablespoon (28 g) neutral oil, 1 (56 g) whole egg, 1 (30 g) egg white, 1 tablespoon (13 g) vanilla extract
Sift in half the dry ingredients and slowly mix, then add all the buttermilk and mix for 20 seconds, then add the remaining dry ingredients and mix until just incorporated. You don't want to over mix this batter.
1¼ cups (150 g) all purpose flour, ¾ teaspoon (3 g) baking powder, ¼ teaspoon (1 g) baking soda, ¼ teaspoon (1.5 g) salt, ½ cup (125 g) buttermilk
Pour into the prepared pan and bake for 20-25 minutes, until a toothpick inserted comes out clean.

Add softened butter to a medium bowl, and using a hand mixer with beater attachment, beat until completely smooth, about 1-2 minutes. Add the salt and powdered sugar ½ cup at a time and beat until completely smooth and combined. At first it will look sandy, but as you beat, the butter will incorporate with the powdered sugar.
4 tablespoon (56 g) Unsalted butter, 1 cups (240 g) powdered sugar, ¼ teaspoon (1.5 g) salt
Add sour cream and beat for another minute, then lastly add the melted chocolate and beat again for another minute until completely smooth. If the mixture is a little too thick, you can add a teaspoon of milk or cream to loosen it up a little.
½ cup (87.5 g) dark chocolate, melted, 2 tablespoon (24 g) sour cream
Frost the cooled cake and enjoy. Make sure to keep this cake refrigerated.