Step-by-step directions

1. Make the reduced strawberry purée: Purée 2 cups (16 oz) fresh strawberries in a blender until smooth. Pour into a saucepan over medium heat.
2. Simmer the purée: Cook over medium-low, stirring occasionally, about 20–25 minutes until reduced to roughly 3/4 cup. Cool to room temperature, then refrigerate until completely cold (can chill overnight).
3. Prep pans and oven: Preheat to 350°F (177°C). Line four 8-inch round cake pans with parchment rounds and grease the sides.
4. Dry mix: Sift together 2 1/4 cups flour, 1 1/2 cups cocoa powder, 1 1/2 tsp salt, 2 1/4 tsp baking soda, and 1 tsp baking powder. Whisk and set aside.
5. Cream butter and sugar: In a stand mixer with paddle, beat 1 1/2 cups room-temperature butter and 2 1/4 cups granulated sugar on medium until pale and fluffy (4–5 minutes). Scrape bowl.
6. Add eggs: Reduce speed to medium-low. Add 4 eggs one at a time, mixing after each until just combined. Scrape down bowl.
7. Add sour cream & flavor: Mix 3/4 cup sour cream and a small bowl of 1 1/2 tbsp vanilla + 1 1/2 tbsp instant espresso (dissolved) into the batter on medium until combined.
8. Combine dry and wet: Alternate adding dry ingredients in thirds with 2 additions of 2 1/4 cups buttermilk, starting and ending with dry. Mix just until combined. Divide batter equally across pans (a little over 2 cups per pan).
9. Bake: Bake two layers at a time for 20–25 minutes. A toothpick should come out clean and cakes should spring back lightly. Cool in pans 10 minutes, then transfer to racks to cool completely. Wrap layers if not assembling immediately.
10. Make chocolate ganache: Microwave 1 cup heavy whipping cream with 2 cups dark chocolate chips in 30-second intervals until steaming. Stir to a thick ganache. Set aside to cool until spreadable.
11. Make strawberry buttercream: Beat 3 cups softened unsalted butter in a stand mixer until pale and fluffy (5–6 minutes). Add 6 cups powdered sugar (half of total) one cup at a time on low. Add the cooled reduced strawberry purée and mix. Add remaining powdered sugar one cup at a time. If too stiff, add heavy cream 1 tbsp at a time until desired consistency. Tint with pink gel if desired. Beat on medium-high 5–7 minutes until light.
12. Prepare dipped strawberries: Wash and thoroughly dry the 10 large strawberries. Line a tray with wax paper. Melt 8 oz dark chocolate with 1 tbsp shortening in 30-second microwave bursts, stirring until smooth. Dip berries, shake off excess, chill 5–10 minutes. Melt pink candy melts in 15-second bursts, transfer to a squeeze bottle or small bag, snip corner, and drizzle over set berries. Chill until firm.
13. Assemble the cake: Place a dollop of frosting on a cake board. Add first cake layer. Spread ~1 cup strawberry buttercream. Pipe a double rim around edge, spoon in thin layer of ganache, and spread. Sprinkle a handful of diced strawberries. Repeat for remaining layers. Place final layer upside down (flat side up).
14. Crumb coat and chill: Frost a thin crumb coat of buttercream. Chill 30 minutes. Apply final thicker coat of frosting. Chill another 30 minutes (or 10–20 minutes in freezer).
15. Ganache drip and finish: Pipe remaining ganache around edges to drip; fill center and smooth with an offset spatula. Chill 5–10 minutes to set. Transfer frosting to a pastry bag with a large star tip. Pipe 10 swirls and top each with a chocolate-covered strawberry. Slice and serve.

Tip: If you want a helpful comparison for other baked goods using chocolate-covered strawberries, see this cookie version in case you want a smaller, portable treat: chocolate-covered strawberry cookies.