Heath Bar Recipe

Preheat and prepare pans

Preheat oven to 350°F (175°C). Grease and line two 8- or 9-inch round cake pans with parchment. Lightly flour the sides.

Whisk dry ingredients together: In a large bowl, sift or whisk together the flour, cocoa powder, baking powder, baking soda, and salt until evenly combined.

Mix wet ingredients: In a separate large bowl, whisk together sugar, eggs, milk, oil, and vanilla until smooth and slightly thickened.

Combine and add hot water: Gradually add the dry mixture into the wet mixture, mixing on low speed or whisking until just combined and free of lumps. Stir in the hot water (batter will be thin) until fully incorporated; this yields a moist chocolate cake crumb.

Bake: Divide batter evenly between prepared pans and tap to remove air bubbles. Bake for 28–34 minutes, or until a toothpick inserted near the center comes out with a few moist crumbs but no wet batter.

Cool: Let cakes cool in pans on a wire rack for 10 minutes. Run a knife around the edges, invert onto racks and remove parchment. Cool completely before filling and frosting—at least 1 hour.

Warm cream: Place chopped chocolate in a heatproof bowl. Heat the cream in a small saucepan until just simmering (do not boil).

Make ganache: Pour hot cream over the chopped chocolate and let sit 1 minute. Stir gently from the center until smooth and glossy. If using, stir in the butter for added shine. Let the ganache cool and thicken to a spreadable consistency (about 20–30 minutes at room temperature or faster in the fridge, stirring occasionally).

Beat butter: In the bowl of a stand mixer fitted with the paddle (or using a hand mixer), beat the room-temperature butter on medium-high for 2–3 minutes until very pale and fluffy.

Add sugars: With the mixer on low, gradually add the sifted powdered sugar (one cup at a time) and the packed brown sugar. After each addition, mix until incorporated. Scrape down the bowl as needed.

Add cream and flavor: Add the heavy cream, vanilla, and salt. Increase speed to medium-high and beat 2–3 minutes until light, creamy, and spreadable. If the buttercream is too stiff, add an extra teaspoon or two of cream; if too loose, add a tablespoon of powdered sugar.

Fold in toffee pieces: Using a spatula, fold in the finely chopped 1 cup of toffee/Heath pieces so they are evenly distributed. Reserve the additional 1 cup of Heath pieces listed under Assembly for extra filling and garnish if desired.

Level and split layers: If cake tops domed, level them with a serrated knife. If you baked two layers, slice each horizontally for up to four thin layers, or leave as two thicker layers—this recipe assumes two layers with one fill between them.

Initial crumb coat: Place the first cake layer on a cake board or serving plate. Spread about half of the cooled ganache over the surface, leaving a 1/4-inch border to prevent squeezing out. Sprinkle about 1/2 cup of the chopped Heath pieces over the ganache in an even layer. Spread about 1 1/2 cups of the toffee buttercream on top of the ganache and Heath layer, smoothing to the edges. Add the second cake layer on top and press gently to adhere.

Crumb coat and chill: Apply a thin crumb coat of remaining buttercream over the top and sides to catch crumbs. Smooth as best you can, then chill the cake for 20–30 minutes in the fridge to set the crumb coat.

Final frosting: Apply the remaining buttercream in an even, smooth layer over the chilled cake. Use an offset spatula or bench scraper for clean sides. If you want visible toffee bits in the frosting, gently press the reserved coarse toffee crumbs into the bottom edge of the cake or scatter on top.

Chocolate drip (optional): Warm the extra melted semisweet chocolate slightly (if needed, add 1 tsp neutral oil or butter) until pourable but not hot. Using a spoon or squeeze bottle, apply a drip around the rim allowing chocolate to fall down the sides. Pour a small amount of chocolate into the center and smooth with an offset spatula if desired.

Decorate: Sprinkle remaining chopped Heath pieces and coarse toffee crumbs on top. If you like, pipe a small rosette border of buttercream and place individual Heath pieces on each rosette. Chill briefly (10–15 minutes) to set decor, then bring to room temperature before serving for best texture.