1 teaspoon kosher salt, if using table salt use ½ tsp
1 ½ cups (3 sticks or 340g) butter, room temperature
4 cups (500g) confectioners sugar
3/4 cup (94g) unsweetened cocoa powder
4 tablespoon (60ml) heavy whipping cream
2 teaspoons (10ml) vanilla extract
1/8 teaspoon kosher salt
Place softened butter and granulated sugar into stand mixer fitted with the paddle attachment and mix on medium for 1-2 minutes.
Add milk, oil, vanilla, and eggs and mix on medium for one minute or until ingredients are fully incorporated.
Place dry ingredients into stand mixer and mix on low until fully combined about 1 minute.
Pour batter into prepared pans 8-inch round cake pans. Bake at 350°F for 18-25 minutes. Remove from oven and let cool in pan for about 5 minutes, then turn out onto a cooling rack for at least 30 minutes. Cool completely before frosting.
In the bowl of an electric stand mixer, fitted with whisk attachment whisk butter and sugar on medium-high speed until very pale and fluffy or about five minutes.
Be sure to stop at least once and scrape the bowl.
With the mixer off, add cocoa powder, vanilla, and salt.
Turn mixer on low and blend for about 30 seconds.
One tablespoon at a time, add in heavy cream.
Once all cream has been added and the mixture is mostly combined, turn off the mixer and scrape down the sides of the bowl.
Now turn the mixer onto medium-high to high and whisk for 3-5 minutes or until mixture is lighter and fluffier. The frosting will be shiny and seem to have many large air bubbles throughout and this is exactly what we are going for. (You can smooth those out on the cake if so desired.)