Baking with spirits is a lot of fun. Like vanilla extract, much of the alcohol burns off during baking, leaving you with a variety of delicious flavors in your baked goods. This is especially true of darker, aged spirits like whiskey and rum, where you get lots of potent flavors that can include vanilla and caramel. This Chocolate Rum Sheet Cake offers a grown-up twist on a very classic party cake, adding flavorful rum to a rich chocolate base for a cake that is indulgent, satisfying and big enough to serve a crowd.
The cake is easy to make and, while not quite as fast as a box of cake mix, it doesn’t take long to put together. The chocolate in this cake comes in the form of dark chocolate, which is melted in with butter and stirred into the batter. The dark chocolate brings plenty of chocolate flavor to the cake, but not so much chocolate that it overpowers the flavor of the rum. Both the dark chocolate and melted butter help to create a cake with a dense, soft crumb that is delightful to slice and serve.
While there isn’t a crazy amount of rum in this cake, you’re still going to taste it in each bite. I recommend using a dark rum in the recipe below – sometime like Meyer’s Dark Rum works well – because the darker rum has strong caramel and molasses flavors that not only work well with the chocolate, but carry through on their own. The recipe will still work with a ligher rum, of course, but darker is ideal if you can get it.
The rum will be a little more noticeable in the frosting than in the cake, which definitely gives the dessert an more adult feel. If you aren’t in the mood for something quite as boozy (though I promise you’re not going to catch a buzz when you eat this cake), you can substitute the rum in the frosting for milk or simply opt for a plain chocolate frosting instead.
During baking, the cake may rise up to have a slightly domed top, but the cake should have a relatively flat, even top once it has cooled completely. This flat top is desirable in sheet cakes because it makes them easy to frost and creates a good surface for writing and decorations. I kept this cake quite simple, of course, but you can think of it as a blank canvas for a birthday message. You can also simply add a few sprinkles or chocolate shavings to dress it up, if desired.
Chocolate Rum Sheet Cake
3/4 cup butter
4 oz dark chocolate, chopped
2 cups all purpose flour
2 cups sugar
1 tsp baking soda
1 tsp salt
3 large eggs
1 cup milk
1/4 cup dark rum
2 tsp vanilla extract
Preheat oven to 350F. Lightly grease a 9Ã—13-inch sheet pan. If desired, line pan with parchment paper (to make it possible to lift the whole cake out of the pan).
In a microwave-safe bowl or a small saucepan, melt the butter. Add dark chocolate and stir until melted. Set aside to cool slightly.
In a large bowl, whisk together flour, sugar, baking soda and salt until well-blended.
In a small bowl, whisk together eggs, milk, rum and vanilla extract. Pour milk mixture into the flour mixture and whisk until completely combined. Pour in butter mixture and whisk until batter is smooth and uniform. Pour batter into prepared pan.
Bake for 40-45 minutes, or until a toothpick inserted into the center of the cake comes out clean or with only a few moist crumbs attached.
Allow cake to cool completely in the pan.
When cooled, frost with Vanilla Rum Buttercream (below)
Makes 1 sheet cake; Serves 15-20.
Vanilla Rum Buttercream
1 cup butter, room temperature
2 tbsp dark rum
2 tbsp milk
1 tsp vanilla extract
1/8 tsp salt
3-4 cups confectioners’ sugar
In a large bowl, beat butter until creamy. Add in rum, milk, vanilla, salt and 2 cups confectioners’ sugar. Mix until well-combined and smooth. Gradually blend in remaining confectioners’ sugar until frosting is thick, smooth and spreadable.
Makes enough for 24 cupcakes/1 9×13-inch sheet cake