Name: Rosette Chocolate Cake with Purple Buttercream Frosting Recipe
Prep time: 30 min
Cook time: 27 min
Total time: 1 h 30 min
Cuisine: American
Ingredients: 2 cups all-purpose flour (260 grams); 2 cups granulated sugar (400 grams); 3/4 cup unsweetened cocoa powder, sifted (75 grams); 2 tsp baking powder (8 grams); 1 1/2 tsp baking soda (9 grams); 1 tsp fine salt (6 grams); 1 cup very hot water (237 grams); 2 tsp instant espresso or coffee (6 grams); 1 cup buttermilk, room temperature (240 grams); 1/2 cup vegetable or canola oil (120 grams); 2 tsp vanilla extract or vanilla bean paste (8 grams); 1 tsp vinegar (4 grams); 2 large eggs, room temperature (112 grams); 3 cups unsalted butter, room temperature (678 grams); 1 Tbsp vanilla extract or vanilla bean paste (12 grams); 1 tsp fine salt (6 grams); 10 cups powdered sugar (1250 grams); 1/3 cup heavy whipping cream, room temperature (75 grams); Purple food coloring, to desired intensity; Open star piping tip; Large piping bag; Offset spatula; Greaseproof cake board or plate

Jump to Recipe

Introduction

The Rosette Cake is a stunning dessert that combines moist chocolate layers with creamy purple buttercream decorated in beautiful rosettes. Perfect for special occasions, this cake is as delicious as it is impressive to look at.

A round cake covered fully in thick, swirled purple frosting in the shape of rosettes, arranged closely together in three horizontal layers from top to bottom. The frosting has a smooth, slightly textured look with the rosettes creating a floral pattern that covers the entire surface and sides of the cake. The cake sits on a white round cake board, which is placed on a shiny silver turntable, all set against a white marbled texture background. Photo taken with an iphone --ar 4:5 --v 7

Ingredients

2 cups all-purpose flour (260 grams)
2 cups granulated sugar (400 grams)
3/4 cup unsweetened cocoa powder, sifted (75 grams)
2 tsp baking powder (8 grams)
1 1/2 tsp baking soda (9 grams)
1 tsp fine salt (6 grams)
1 cup very hot water (237 grams)
2 tsp instant espresso or coffee (6 grams)
1 cup buttermilk, room temperature (240 grams)
1/2 cup vegetable or canola oil (120 grams)
2 tsp vanilla extract or vanilla bean paste (8 grams)
1 tsp vinegar (4 grams)
2 large eggs, room temperature (112 grams)
3 cups unsalted butter, room temperature (678 grams)
1 Tbsp vanilla extract or vanilla bean paste (12 grams)
1 tsp fine salt (6 grams)
10 cups powdered sugar (1250 grams)
1/3 cup heavy whipping cream, room temperature (75 grams)
Purple food coloring
Open star piping tip
Large piping bag

Instructions

Step 1: Preheat your oven to 350°F. Line three 8-inch or four 7-inch cake pans with parchment paper rounds and grease them with non-stick baking spray. If you don’t have enough pans, bake the layers in batches; the batter will hold for an hour or two at room temperature.
Step 2: In a large bowl, whisk together the flour, sugar, cocoa powder, baking powder, baking soda, and salt until fully combined.
Step 3: In a medium bowl, dissolve the instant espresso or coffee into the hot water. Then stir in buttermilk, oil, vanilla extract, and vinegar until just combined.
Step 4: Pour the wet ingredients into the dry ingredients and mix by hand until fully incorporated.
Step 5: Add the eggs one at a time, stirring well after each addition. The batter will be thin, which is expected.
Step 6: Divide the batter evenly among the prepared pans and bake for 24 to 27 minutes, or until a toothpick inserted in the center comes out clean.
Step 7: Let the cakes cool in the pans for 5 minutes, then run an offset spatula around the edges to loosen them. Transfer to the freezer for 30 minutes to speed up cooling. Once cool, remove from the pans and level the tops with a serrated knife.
Step 8: To make the purple buttercream, beat the unsalted butter on medium speed until smooth, about 1-2 minutes. Add vanilla extract and salt, mixing on low.
Step 9: Gradually add powdered sugar while mixing slowly. Halfway through, pour in the heavy cream to help achieve a smooth consistency. Continue mixing until the frosting is light and fluffy.
Step 10: Add purple food coloring to your desired shade, scraping the bowl to ensure an even color throughout. Cover to prevent crusting and set aside.
Step 11: Assemble the cake by stacking and frosting each layer on a greaseproof cake board or plate, using a small amount of frosting to secure the bottom layer.
Step 12: Apply an even layer of purple buttercream between each cake layer, then spread a thin crumb coat around the entire cake. Smooth with a bench scraper and chill for 30 minutes in the fridge or 10 minutes in the freezer.
Step 13: Fill a large piping bag fitted with an open star tip with the remaining frosting. Seal the top to avoid mess.
Step 14: Create two evenly spaced horizontal guide lines around the cake using an offset spatula or butter knife. These will help you pipe three even rows of rosettes.
Step 15: Pipe rosettes along the bottom guide, working in the same direction and taking breaks if needed. Repeat the process for the middle and top rows, then fill the top of the cake with rosettes, piping from the edge inward.
Step 16: For a neat finish, end each rosette where the next one begins to hide the tail underneath the following rosette.
Step 17: Chill the decorated cake in the fridge for at least 30 minutes to allow the rosettes to set before serving.

Tips & Variations

If you don’t have instant espresso, strong brewed coffee works well as a substitute to enhance the chocolate flavor.
Use gel or paste food coloring for a more vibrant purple without thinning the buttercream.
If the frosting feels too thick, add a bit more heavy cream, a teaspoon at a time, until you reach the desired consistency.
For faster cooling, place the cake layers in the freezer but wrap them tightly if freezing for longer storage.
Try adding a layer of raspberry jam between cake layers for a fruity twist.

Storage

Store the cake covered in the refrigerator for up to 4 days. Let it sit at room temperature for 20-30 minutes before serving for the best texture. You can freeze the unfrosted cake layers wrapped tightly in plastic wrap for up to 3 months; thaw in the refrigerator before frosting and assembling.

How to Serve

A round cake with a smooth, even layer of lavender-purple frosting on top and around the sides is placed on a white cake stand with a marbled white surface beneath. The woman’s hand is holding the cake stand steady while another woman’s hand pipes large, thick rosettes of the same lavender frosting around the bottom half of the cake, forming two neat rows of swirl shapes with detailed ridges. The frosting looks creamy and soft, and the cake is sitting on a white cake board above the stand. Photo taken with an iphone --ar 4:5 --v 7

Serve this delicious recipe with your favorite sides.

FAQs

Can I use regular milk instead of buttermilk?

Yes, you can substitute regular milk mixed with 1 tablespoon of vinegar or lemon juice per cup to mimic buttermilk’s acidity needed for the cake to rise properly.

How do I prevent the rosettes from melting?

Keep the cake chilled during decorating and after assembly. Avoid working in a warm environment and use cold butter for the frosting to help maintain the shape of the rosettes.