½ cup (120ml) whole milk
2 teaspoons freshly squeezed lemon juice
2 cups (260g) all-purpose flour
¼ cup (25g) unsweetened Dutch-processed cocoa powder
2 teaspoons baking powder
½ teaspoon baking soda
½ teaspoon kosher salt
8 tablespoons (1 stick/115g) unsalted butter, at room temperature
1 ½ cups (300g) granulated sugar
2 teaspoons pure vanilla extract
3 large eggs, at room temperature
1 cup (230g/8oz) full fat sour cream
2 tablespoons red food coloring
1—Preheat the oven to 350°F/180°C. Grease two 8 by 2- inch pans with butter, line the bottom and sides with parchment paper, and grease the paper.
2—Add the lemon juice to the milk to sour it. Set aside for 5 to 10 minutes or until curdled.
3—Place a large sifter or a sieve in a large mixing bowl. Add the flour, cocoa powder, baking powder, baking soda, and salt and sift.
4— Using an electric mixer with beaters or a paddle attachment, beat the butter for 30 seconds on medium speed and then gradually add the sugar. Scrape down the sides of the bowl. Continue beating on medium speed for another 4 minutes or until light in color and fluffy.
5— Add the vanilla extract and beat until combined.
6— With the mixer still on medium speed, gradually add the eggs. If the batter curdles, add 1 to 2 tablespoons of the flour to bind it back together.
7— On low speed, alternate between adding the flour mixture and the milk. Add the sour cream and food coloring; mix until just combined. Don’t overbeat. Scrape down the sides and bottom of the bowl.
8—Pour the batter into the prepared pans and smooth the top. Bake in the center of the oven for 25-30 minutes, or until a wooden skewer inserted in the center comes out clean, and the cake bounces back when lightly pressed.
9— Remove the cake from the oven and let it stand for 10 minutes. Run a butter knife around the cake to gently release. Invert the cake, peel off the parchment paper, and cool on a wire rack. Ice once the cake has completely cooled.