Black Magic Snack Cake with Cocoa Frosting
A classic sheet cake with deep chocolate flavor from cocoa and strong coffee. The thin batter creates a tender crumb while the creamy cocoa frosting adds richness. Serve at potlucks, bake sales, or casual gatherings. This version uses coffee to amplify chocolate notes without adding coffee flavor.
Ingredients
- 2 cup sugar, granulated
- 1 ¾ cup all-purpose flour, or cake flour
- ¾ cup unsweetened cocoa powder, sifted
- 2 teaspoon baking soda, leveled
- 1 teaspoon baking powder, leveled
- 1 teaspoon salt, fine
- 2 eggs, room temperature2 flax eggs (2 tablespoons ground flaxseed + 6 tablespoons water, sit 15 minutes)1:1vegan
medium
Full guide → - 1 cup buttermilk, room temperature
- 1 cup strong black coffee, brewed, cooled slightly
- ½ cup vegetable oil, neutral
- 1 teaspoon vanilla extract, pure
- ⅝ cup unsweetened cocoa powder, for frosting
- ½ pound butter, unsalted, softened
- 3 cup powdered sugar, sifted
- ⅓ cup milk, whole or 2%
Instructions
- 1
Heat oven to 350°F and grease and flour a 13 x 9 x 2-inch baking pan.
- 2
Whisk together sugar, flour, cocoa, baking soda, baking powder, and salt in a large bowl.
- 3
Add eggs, buttermilk, coffee, oil, and vanilla; beat on medium speed for 2 minutes until thin batter forms.
- 4
Pour batter evenly into prepared pan.
- 5
Bake for 35 to 40 minutes until a wooden pick inserted in the center comes out clean.
- 6
Cool on a wire rack.
- 7
For frosting, melt butter and stir in cocoa powder.
- 8
Alternately add powdered sugar and milk, beating until spreading consistency is reached.
- 9
Add additional milk as needed and stir in vanilla.
- 10
Frost the cooled cake.
Tips
Use strong brewed coffee at room temperature to enhance chocolate without making the cake taste like coffee; instant espresso powder also works.
Beat the batter for the full 2 minutes to develop structure; the thin consistency is intentional and yields a moist crumb.
Sift cocoa and powdered sugar separately to eliminate lumps in both batter and frosting for smooth texture.
Good to Know
Cover and refrigerate up to 4 days. Store at room temperature in airtight container up to 2 days.
Bake cake 1 day ahead; frost just before serving or up to 4 hours ahead. Frosting sets slightly when chilled.
Serve at room temperature with coffee, milk, or ice cream. Cut into 12-16 squares.
Common Mistakes
Do not skip beating the batter for 2 minutes to avoid a dense, flat cake.
Do not frost the cake while warm to avoid frosting melting and sliding off.
Do not over-beat the frosting after reaching spreading consistency to avoid breaking the emulsion.
Substitutions
Dairy-Free Swaps
none
Vegan Options
medium
Full guide →General Alternatives
FAQ
Can I make this ahead for a party?
Yes. Bake the cake up to 1 day ahead and store covered at room temperature. Make frosting and frost 4-6 hours before serving, or frost just before serving and refrigerate.
What if my frosting is too thick to spread?
Add milk 1 tablespoon at a time while beating until you reach spreading consistency. If too thin, add sifted powdered sugar gradually.
Can I freeze this cake?
Yes. Wrap unfrosted cake tightly in plastic wrap and foil; freeze up to 3 months. Thaw at room temperature before frosting. Frosted cake freezes up to 1 month.