Cinnamon Mocha Sheet Cake

1 cup butter

⅓ cup unsweetened cocoa powder

1 cup water

2 tablespoons instant espresso powder

1 cup white sugar

1 cup brown sugar

2 cups all-purpose flour

1 ½ teaspoons ground cinnamon

1 teaspoon baking soda

1 teaspoon vanilla extract

½ cup milk

2 eggs, lightly beaten

¼ cup butter

3 tablespoons unsweetened cocoa powder

3 tablespoons strong brewed coffee

½ teaspoon ground cinnamon

1 tablespoon milk, or more as needed

2 cups sifted confectioners sugar

Preheat oven to 350 degrees F (175 degrees C). Grease a 10x15-inch jelly roll pan.

Melt 1 cup butter in a saucepan over medium heat. Whisk in 1/3 cup cocoa powder, water, and espresso powder; mix until smooth.

Combine white sugar, brown sugar, flour, 1 1/2 teaspoon cinnamon, and baking soda in a mixing bowl. Pour in the butter-cocoa mixture, vanilla extract, 1/2 cup milk, and eggs. Mix until fully incorporated. Pour the batter into the prepared baking sheet

Bake in the preheated oven until the cake springs back when touched lightly with a finger, about 18 minutes. Cool the cake in the pan on a wire rack.

To make the icing, melt 1/4 cup butter in a saucepan or in the microwave. Transfer melted butter to a mixing bowl. Whisk in 3 tablespoons cocoa powder, coffee, 1/2 teaspoon cinnamon, and 1 tablespoon milk. Slowly mix in the sifted confectioners sugar and beat until smooth; add milk as needed to reach the consistency you like. Spread the icing over the cooled cake. For easier serving, score the icing before cutting the cake: mark lines as a guide before you start to cut, and divide the cake into 32 pieces.