Step 1

Make the cake: Preheat the oven to 350 degrees with the rack in the middle. Grease and flour two 9-inch round cake pans. In a medium bowl, whisk together the flour, salt, baking powder and baking soda. In the bowl of a stand mixer fitted with a paddle attachment, beat together the butter, oil and sugar on medium until light and fluffy, 3 to 5 minutes. Stop the mixer and scrape down the sides of the bowl. Add the eggs, one at a time, beating on medium for 1 minute between each addition. Beat in the vanilla extract. Add half of the dry ingredients to the batter and beat on low speed while slowly streaming in the milk. Add the remaining dry ingredients and beat on low until just combined. Stop the mixer and scrape down the sides of the bowl. Increase the speed to medium and beat for 2 minutes more to aerate the batter. Evenly divide the batter between the pans. Bake for 25 to 30 minutes, until a tester inserted in the center of the cake comes out with only a few crumbs, and the top springs back when gently pressed. Remove the cake layers from the oven and let cool in the pans for 15 minutes before running a butter knife along the perimeter and inverting onto wire racks. Cool completely before frosting. You can also wrap the layers in plastic wrap and refrigerate overnight before frosting. Make the frosting: In the bowl of a stand mixer fitted with a paddle attachment, beat together the butter, cocoa powder and salt until well combined, about 3 minutes. The mixture will be very thick. Turn off the mixer and scrape down the sides of the bowl to thoroughly incorporate the ingredients. Add the powdered sugar and start the mixer on low, then add the milk and vanilla extract. As the sugar incorporates, raise the speed of the mixer to medium and whip the frosting until smooth and thick, about 1 minute. In a liquid measuring cup, stir together the heavy cream and Ovaltine powder. The mixture won’t be completely smooth; that’s okay. Turn the mixer to low speed and pour the cream mixture into the frosting in a slow, steady stream. Stop the mixer to scrape down the sides of the bowl, then beat on medium speed until the frosting is soft and creamy, about 1 minute. Frost the cake: If your cake layers domed at the top during baking, use a serrated knife to trim them so both layers are level. Place the first cake layer, top-side down, on a flat plate or cake stand. Spoon a generous 1/2 cup (120 ml) of the frosting onto the cake layer and, using an offset spatula, evenly spread the frosting across, letting it sneak over the edges of the cake. Place the second cake layer on the first, top-side down. Spoon another generous 1/2 cup of frosting on top and, using an offset spatula, evenly spread the frosting across, letting some of it cascade over the edges. Rinse the offset spatula in warm water and shake off excess water. Scoop a few tablespoons of buttercream onto the tip of the offset spatula. Holding the spatula vertically, use a short sweeping motion to spread the frosting across the sides, spreading in a very thin layer. You should be able to see the sides of the cake layers through this first layer of buttercream. Place the cake in the refrigerator to chill and set for 20 minutes. This is called a crumb coat — a layer of buttercream that will seal in any cake crumbs, allowing the second layer of buttercream to flow smoothly across the cake without fighting any crumbs.

Step 2

Remove the cake from the refrigerator and spread a second layer of buttercream across the top of the cake, allowing some frosting to cascade over the edges. Scoop of a few tablespoons of buttercream onto the offset spatula and generously spread across the sides of the cake all the way around. As you smooth frosting along the side of the cake, clean the spatula with warm water anytime too much buttercream has accumulated — this will help smooth the sides of the cake. Refrigerate the cake for at least 1 hour before serving to allow the frosting to harden and the cake to set.