Ingredients
- ½ cup (100 g) granulated sugar, divided
- ½ cup fresh or frozen cranberries
- Nonstick vegetable oil spray
- 1½ cups (300 g) granulated sugar
- ⅔ cup (57 g) Dutch-process cocoa powder (such as Guittard Cocoa Rouge)
- 2 tsp. Diamond Crystal or 1¼ tsp. Morton kosher salt
- 2 tsp. instant espresso powder
- ½ cup plus 6 Tbsp. (1¾ sticks) unsalted butter, melted, slightly cooled
- 3 large eggs
- 1 cup sour cream
- 1 Tbsp. vanilla extract
- 1¼ cups (156 g) all-purpose flour
- 1¾ tsp. baking powder
- 6 oz. unsweetened chocolate, chopped, or 1 cup unsweetened chocolate chips
- 6 oz. white chocolate, chopped, or 1 cup white chocolate chips
- 1½ cups (3 sticks) unsalted butter, room temperature
- 3 cups (330 g) powdered sugar, sifted, plus more for dusting
- 1 Tbsp. vanilla extract
- 1 tsp. Diamond Crystal or ½ tsp. Morton kosher salt
- Rosemary sprigs (for decorating)
Steps
- Bring ¼ cup (50 g) granulated sugar and ¼ cup water to a boil in a small saucepan over medium heat, whisking occasionally, until sugar is dissolved, 2–3 minutes. Let simple syrup cool 5 minutes.
- Add ½ cup fresh or frozen cranberries to simple syrup and stir until coated. Using a slotted spoon, transfer cranberries to a wire rack set inside a rimmed baking sheet and let sit at least 1 hour and up to 1 day to dry.
- Place remaining ¼ cup (50 g) granulated sugar in a small bowl and, working one at a time, toss cranberries in sugar to coat. Transfer to a plate or bowl as you go; set aside. Do Ahead: Cranberries can be sugared 3 days ahead. Transfer to an airtight container; cover and chill.
- Place a rack in middle of oven; preheat to 325°. Lightly coat a 9×5" loaf pan with nonstick vegetable oil spray. Whisk 1½ cups (300 g) granulated sugar, ⅔ cup (57 g) Dutch-process cocoa powder,, 2 tsp. Diamond Crystal or 1¼ tsp. Morton kosher salt, and 2 tsp. instant espresso powder in a large bowl to combine. Add ½ cup plus 6 Tbsp. (1¾ sticks) unsalted butter, melted, slightly cooled, and whisk until just combined. Add 3 large eggs, one at a time, whisking after each addition until incorporated and smooth. Add 1 cup sour cream and 1 Tbsp. vanilla extract and whisk until smooth. Add 1¼ cups (156 g) all-purpose flour and 1¾ tsp. baking powder and whisk until combined and no dry streaks remain (a few small lumps are okay).
- Scrape batter into prepared pan to fill three fourths full. (Do not overfill. If your loaf pan holds less than 7 cups you may have leftover batter.) Smooth surface with an offset spatula. Bake cake until a tester inserted into the center comes out clean, 65–80 minutes. Transfer pan to a wire rack and let cake cool in pan 30 minutes. Run spatula around edges of cake, then turn out onto rack. Let cake cool completely. Do ahead: Cake can be baked 3 days ahead. Store tightly wrapped at room temperature.
- Microwave 6 oz. unsweetened chocolate, chopped, or 1 cup unsweetened chocolate chips in a microwave-safe bowl in 15-second bursts, stirring after each burst, until melted, 1–2 minutes; set aside. Add 6 oz. white chocolate, chopped, or 1 cup white chocolate chips to another microwave-safe bowl and microwave in 15-second intervals, stirring after each burst, until melted, 1–2 minutes. Set aside separately.
- Beat 1½ cups (3 sticks) unsalted butter, room temperature, 3 cups (330 g) powdered sugar, sifted, 1 Tbsp. vanilla extract, and 1 tsp. Diamond Crystal or ½ tsp. Morton kosher salt in the bowl of a stand mixer fitted with the paddle attachment on medium-high speed, scraping down sides of bowl as needed, until light and fluffy, about 2 minutes.
- Transfer half of the buttercream (about 1¼ cups) to bowl of reserved melted white chocolate. Stir with a rubber spatula until smooth. (Mixture might appear grainy at first, but keep stirring and it will smooth out. Some texture is fine.) Add melted unsweetened chocolate to remaining buttercream and fit back onto mixer; beat on medium-high speed until just combined, about 1 minute.
- If the top of the cake has overflowed slightly around the edges, trim, to create an evenly rounded top. (Do not cut the top so it’s flat.) Place cake on a cutting board and use a serrated knife to cut into thirds lengthwise (you should have 3 long layers). Place bottom cake layer on a platter or large plate and spread half of vanilla buttercream evenly over with rubber or offset spatula. Place middle cake layer on top and spread remaining vanilla buttercream over. Set top cake layer on top. Spread half of chocolate buttercream around sides of cake. Chill cake at least 30 minutes and up to 2 hours. Loosely cover remaining chocolate buttercream in bowl and set aside at room temperature.
- Remove cake from refrigerator and frost all over with reserved chocolate buttercream to cover completely. Drag a fork through frosting to make textured lines all over the cake (you want it to resemble tree bark). Chill cake at least 1 hour to let buttercream set.
- Just before serving, place some powdered sugar in a fine-mesh sieve and dust cake. Decorate with sugared cranberries and rosemary sprigs as desired to resemble holly. Do ahead: Cake can be assembled 1 day ahead. Keep chilled.