Preheat the oven to 350°F (175°C). Grease and lightly flour two 9-inch round cake pans, or line bottoms with parchment.

In a large bowl, whisk together flour, sugar, cocoa powder, baking powder, baking soda, and salt until uniform.

Add eggs, milk, vegetable oil, and alcohol-free vanilla extract. Beat or whisk until smooth and homogenous.

Carefully pour in the cup of boiling water and stir until the batter is smooth. The batter will be thin — that’s expected and helps create a moist crumb.

Divide batter evenly between the prepared pans. Bake for 30–35 minutes, or until a toothpick inserted in the center comes out with a few moist crumbs.

Let cakes cool in the pans for about 10 minutes, then turn them out onto wire racks to cool completely before frosting.

Beat the softened butter on medium speed until creamy, about 2 minutes.

Gradually add powdered sugar, alternating with the 1/2 cup milk, until you reach a spreadable consistency. Mix in the vanilla.

If too thick, add milk 1 teaspoon at a time; if too thin, add more powdered sugar.

Level cakes if needed. Place the first layer on a serving plate, spread a generous layer of frosting, and set the second layer on top.

Crumb-coat if you like. Finish with a smooth top coat of buttercream and garnish with sprinkles or edible flowers.