1-Preheat your oven: preheat your oven to 350°F (175°C) and spray the bottoms of two 6-inch cake pans with non-stick spray to keep things easy. If you’re using one deep 3-inch pan for a single layer, that’s fine too just watch the bake time closely.

2-Sift together: sift together half cup all-purpose flour, 7 tablespoons granulated sugar, 3 tablespoons unsweetened Dutch-processed cocoa powder, half tablespoon instant espresso powder, quarter teaspoon baking soda, one eighth teaspoon baking powder, and quarter teaspoon coarse Kosher salt in a bowl. This step helps everything mix evenly and avoids lumps.

3-Add and whisk: add 1 large egg at room temperature, quarter cup whole milk at room temperature, quarter cup sour cream at room temperature, quarter cup vegetable oil, and 1 teaspoon vanilla extract, whisking until fully combined for about 15 seconds.

4-Bake: divide the batter evenly between the pans, and bake on the center rack for 15 to 16 minutes until the tops spring back or a toothpick comes out clean. While the cake cools on a wire rack covered with a kitchen towel, you can move on to the buttercream.

5-Beat buttercream: For the buttercream, beat 1 cup unsalted butter on medium speed for 1 minute until smooth, then gradually add 1 and one half cups powdered sugar, half cup unsweetened Dutch-processed cocoa powder, half tablespoon meringue powder if you’re using it, and one eighth teaspoon coarse Kosher salt on low speed.

6-Finalize buttercream: Add 1 teaspoon vanilla extract and whip on medium speed for 4 to 5 minutes until light and fluffy, scraping the bowl as needed. If the mixture is too thick, stir in 1 to 2 tablespoons milk. Finally, mix on low speed for 2 minutes to smooth it out.

7-Assemble cake: Once everything is ready, remove the cooled cakes from the pans, fill and frost with the buttercream, and sprinkle 2 tablespoons semi sweet mini chocolate chips on top for a fun finish.