2c. good-quality unsweetened cocoa powder, plus more for dusting
3c. all-purpose flour
21/2c. granulated sugar
2tsp. baking powder
1tsp. baking soda
1/4c. plus 3 Tbsp vegetable oil
11/4c. sour cream
11/2c. strong hot coffee
5 large eggs, beaten
1tbsp. pure vanilla extract
8oz. strawberries, hulled
31/2 sticks unsalted butter, softened
7c. confectioners’ sugar
3oz. dark chocolate, chopped
4tbsp. unsalted butter
Heat oven to 350ºF. Grease sides of two 8-in. round cake pans with butter, than dust sides with cocoa powder (tap out excess). Line bottoms with parchment.
Make cake: In large bowl, whisk together flour, sugar, cocoa powder, baking powder, baking soda, and salt. In large measuring cup or bowl, mix together oil, sour cream, coffee, eggs, and vanilla. Add wet ingredients to flour mixture and whisk to combine.
Divide mixture evenly between prepared pans and bake until wooden pick inserted into center of cakes comes out clean, 50 to 55 minutes. Cool cakes in pans 5 minutes, then transfer to wire rack to cool completely.
Make buttercream: Roughly chop strawberries. Add to blender or food processor and puree until smooth. Set aside. using electric mixer, beat butter to soften. Sift in half of confectioners’ sugar and slowly mix to combine. Sift in remaining sugar, add strawberry puree, and mix to combine. Increase speed and beat until light and fluffy, about 30 seconds.
Trim cakes to level if needed. Slice each cake in half horizontally to make 4 layers. Sandwich all 4 layers together, dividing roughly half of buttercream and spreading between each pair. Next, spread scant layer of buttercream over top and sides of cake. Refrigerate 20 minutes. Transfer cake to stand or board.
Frost cake with remaining buttercream. Refrigerate 20 minutes. Meanwhile make glaze: Melt chocolate and butter in heatproof bowl set over pan of barely simmering water, stirring until melted and smooth. Cool 5 minutes.
Pour glaze over chilled iced cake, encouraging it to drip down sides. Allow to set 15 minutes before decorating with whole strawberries.