Mahogany Cake

Mahogany Cake Recipe:
2 cups all purpose flour or cake flour
3 Tbsp unsweetened cocoa powder
1 tsp baking soda
3/4 tsp salt (optional)
1/2 cup unsalted butter (room temp)
1/13 cup white granulated sugar
1/4 cup oil (neutral)
1 tsp vanilla extract
2 large eggs (room temp)
1 1/4 cup whole buttermilk (room temp)
Ermine Frosting Recipe:
2 cups whole milk
2/3 cup all purpose flour
2 cups white granulated sugar
1 tsp kosher salt
2 cups unsalted butter softened
2 tsp vanilla extract