This classic chocolate sheet cake with colorful homemade sprinkles is always such a crowd pleaser! Unlike store-bought sprinkle varieties, these homemade sprinkles only serve to elevate the moist cake and fudge frosting, due to their unique color and delicious taste. They can easily be customized to suit your personal preferences too! Choose your own base flavor such as rose, almond, or coconut. And your favorite color shades too, including pastel pink, baby blue, and neon green. It's a thoughtful cake worthy of a celebration.
How to Make the Homemade Sprinkles
In the bowl of a stand mixer fitted with the beater attachment, or using handheld electric beaters, beat together the confectioners sugar, water, vanilla bean extract, rose water and salt. Mix on medium speed to form a thick paste.
Add a few drops of food dye into various small bowls, using as many dyes as desired for your sprinkles. Divide the sugar paste between the bowls and use a rubber spatula to evenly mix until the mixture is evenly colored.
Line a large baking tray with non-stick parchment paper. Transfer the dyed pastes into their own piping bags, fitted with small tips, then evenly pipe out long and thin lines of the colored mixture. Set the tray aside for 1 to 2 hours to completely dry the sprinkles.
Once dried, use a sharp knife to cut the sprinkle lines into your desired shape and size. Set aside to use on the cake. You can store the sprinkles in an airtight container at room temperature for up to 1 month. Make sure to keep them in a dark, cool place.
How to Make the Chocolate Sheet Cake
Pre-heat the oven to 350 Fahrenheit (180 Celsius). Grease and line an 8-inch (20 centimetres) rectangular baking tin. Let the parchment paper slightly overhang the sides.
Place the instant coffee powder and boiling water into a measuring cup. Stir until the granules are dissolved. Set aside to cool.
In a large mixing bowl, whisk together the all-purpose flour, Dutch-processed cocoa powder, baking soda, baking powder and salt. Stir in the sugar. Add in the whole milk, vegetable oil, eggs and vanilla bean extract. Whisk until evenly combined and glossy. Pour in the brewed and cooled coffee and whisk until smooth. The batter should be very thin and runny. Pour the batter into the prepared baking tin.
Bake, for 30 to 32 minutes, or until risen and a skewer inserted into the middle comes out with a few moist crumbs attached. Remove from the oven and let the cake cool in its tin for 15 minutes, before carefully turning it out and onto a wire rack, to cool completely before frosting.
How to Make the Frosting
Again, place the instant coffee powder and boiling water into a measuring cup. Stir until the granules are dissolved. Set aside until completely cool.
In the bowl of a stand mixer fitted with the beater attachment, or using handheld electric beaters, beat together the butter and sugar on medium speed, until light and creamy, 3 to 5 minutes. Pause mixing to scrape down the bottom and sides of the bowl as needed. Pour in the melted dark chocolate. Increase the mixer speed to medium-high and beat until well combined, two more minutes. Add in the Dutch-processed cocoa powder, cream, vanilla bean extract and salt. Beat until just combined then pour in the cooled coffee. Increase the mixer speed to high and beat for a further two minutes, until very smooth and fluffy.
Set the chocolate sheet cake out and onto a serving plate or cake stand. Using an offset spatula or the back of a metal spoon, generously spread the frosting into swoops and swirls over the top of the cake.
Decorate the cake with a handful of the homemade sprinkles before slicing and serving.
The cake is best eaten on the day of making, but can be kept in an airtight container, stored at room temperature for a few days.