Guinness Chocolate Sheet Cake with Irish Cream Frosting Recipe

Big pan. Bold flavor. Built for a crowd. This Guinness Chocolate Sheet Cake brings deep cocoa character, extra moisture from stout, and a smooth Irish cream frosting that turns a simple sheet cake into a holiday centerpiece. It is rich without feeling heavy, soft without falling apart, and made to slice clean for parties, potlucks, and St. Patrick’s Day dessert tables.

Baked in a Fat Daddio’s POB-12182 pan, this cake gets the kind of even bake a large-format dessert needs. When working with a batter this generous, even distribution matters. Pour the batter into the pan and use an offset spatula to gently level the surface before it goes into the oven. That simple step helps the cake bake evenly from corner to corner. Once baked, let the cake cool completely before frosting. A warm cake will soften the butter in the Irish cream frosting and turn that smooth topcoat into a slippery mess. For the cleanest finish, frost the cake right in the pan, then slice and serve.

Ingredients for Guinness Chocolate Sheet Cake

This recipe yields one 12 x 18 x 2 inch sheet cake.

For the chocolate stout cake

• 1 1/2 cups (340 grams) unsalted butter

• 1 1/2 cups (128 grams) unsweetened cocoa powder

• 2 cups (480 milliliters) Guinness or other stout beer

• 3 cups (600 grams) granulated sugar

• 1 cup (220 grams) packed light brown sugar

• 4 large eggs, room temperature

• 1 tablespoon vanilla extract

• 3 cups (360 grams) all-purpose flour

• 1 teaspoon baking soda

• 1 teaspoon baking powder

• 1 1/2 teaspoons salt

• 1 cup (240 grams) sour cream

For the Irish cream frosting

• 1 cup (226 grams) unsalted butter, softened

• 4 1/2 cups (540 grams) powdered sugar

• 3 to 4 tablespoons Irish cream liqueur

• 1 teaspoon vanilla extract

• 1 to 2 tablespoons heavy cream, as needed

• Pinch of salt

Step-by-Step Baking Instructions

Prepare the pan and oven

1. Preheat your oven to 325° F (163° C).

2. Grease your Fat Daddio’s POB-12182 pan and line the bottom with parchment paper if desired for easier serving and cleanup.

Make the chocolate stout base

1. In a medium saucepan over low heat, melt the butter.

2. Whisk in the cocoa powder until smooth.

3. Slowly pour in the stout and whisk until fully combined and glossy.

4. Remove from the heat and let the mixture cool for 5 to 10 minutes.

Mix the batter

1. In a large bowl, whisk together the granulated sugar, brown sugar, eggs, and vanilla extract until smooth.

2. Whisk in the sour cream until fully incorporated.

3. Gradually add the slightly cooled chocolate stout mixture and whisk until uniform.

Add the dry ingredients

1. In a separate bowl, whisk together the flour, baking soda, baking powder, and salt.

2. Add the dry ingredients to the wet ingredients in two additions, mixing just until combined after each addition.

3. Do not overmix. The batter should be smooth and pourable.

Fill and level the pan

1. Pour the batter into the prepared POB-12182 pan.

2. Use an offset spatula to gently spread and level the batter into the corners and across the surface.

3. Make sure the depth looks even from edge to edge. Uneven batter depth leads to uneven baking.

Bake the cake

1. Bake for 28 to 36 minutes, or until the center is set and a toothpick inserted near the middle comes out with a few moist crumbs.

2. Avoid overbaking. This cake should stay moist and tender.

Cool completely

1. Place the pan on a wire rack and let the cake cool completely in the pan.

2. Do not frost while warm. Even a slightly warm cake can melt the frosting and leave the top loose and glossy instead of smooth and structured.

Make the Irish Cream Frosting

1. In a large bowl, beat the softened butter until smooth and creamy.

2. Add the powdered sugar gradually, mixing on low speed at first.

3. Add the Irish cream liqueur, vanilla extract, and a pinch of salt.

4. Beat until light and fluffy.

5. Add heavy cream, one tablespoon at a time, if needed to reach a smooth, spreadable consistency.

Frost and Finish

1. Once the cake is fully cooled, spread the frosting directly over the cake while it is still in the pan.

2. Use an offset spatula to create a smooth top or soft swoops, depending on your preferred finish.

3. Slice into squares and serve straight from the pan for a neat, professional presentation.

This Guinness Chocolate Sheet Cake with Irish Cream Frosting lands exactly where a holiday sheet cake should. Rich chocolate crumb. Deep stout flavor. Smooth frosting with just enough warmth and sweetness to round it out. It is easy to serve, hard to forget, and built for the center of the table.

Looking for more baking inspiration? Browse our collection fatdaddios.com/recipes.

---