Chocolate cake with caramel poached pears and chocolate buttercream

Whisk in the butter, 2 cubes at a time, incorporating each addition into the meringue before adding the next. Continue until all the butter is added. The mixture will look curdled at first, but keep whisking and it will come back together. Increase the mixer speed to high and whisk for 2 minutes more. Add both cooled chocolates, then whisk again until combined. Set aside at room temperature until ready to assemble (see Make Ahead).

To assemble, put one cake bottom-side up on a serving plate or cake stand. Drizzle with 2 tbsp of the reduced pear syrup, then spread with a third of the buttercream. Halve, core and thinly slice 2 of the pears, then arrange on top of the buttercream. Sandwich with the second cake. Drizzle more syrup over the top, then pile on the remaining buttercream, creating pillowy waves (or smooth the top and sides to fully frost if you prefer). Dip the poached pears in the reduced syrup so they’re glossy and arrange on top of the cake. Drizzle with more syrup when ready to serve.