Preheat the oven to 350°F (175°C). Grease three 8-inch round cake pans, cut and fit parchment rounds into the bottoms, grease the parchment, then flour the insides of the pans and tap out excess; set pans aside.

In the bowl of an electric mixer (or in a large mixing bowl if using a hand mixer), sift together 2½ cups (312.5 g) plus 1 tablespoon all-purpose flour, 3 cups (600 g) granulated sugar, 1 cup (86 g) plus 1 tablespoon Dutch-process cocoa powder, 1 tablespoon baking soda, 1½ teaspoons baking powder, and 1½ teaspoons salt.

In a medium bowl whisk together 3 eggs (room temperature), 1½ cups (360 ml) buttermilk (room temperature), 1½ cups (355.5 ml) strong hot black coffee, ¾ cup (163.5 ml) vegetable oil, and 4½ teaspoons vanilla extract.

Add the wet ingredients to the dry ingredients and mix on medium speed for 2 minutes. Scrape the sides and bottom of the bowl, then mix an additional 20 seconds. The batter will be very thin.

Divide the batter evenly among the three prepared pans. Bake for 20 minutes, then rotate the pans and continue baking until a toothpick inserted into the center comes out almost clean (with a few moist crumbs), about 12 more minutes.

Remove the pans from the oven and cool the cakes in the pans on wire racks for 20 minutes. Carefully turn the cakes out onto wire racks and cool completely.

While the cakes cool, make the peanut butter frosting: in the bowl of an electric mixer fitted with the paddle attachment, combine 2 cups (240 g) powdered sugar, 2 cups (516 g) creamy peanut butter, 10 tablespoons unsalted butter (room temperature), 1½ teaspoons vanilla extract, and ½ teaspoon kosher salt. Mix on medium-low speed until creamy, stopping to scrape down the bowl as needed.

Add 2/3 cup (158.67 ml) heavy cream to the frosting and beat on high speed until the frosting is light and smooth. Do not overbeat.

Coarsely chop the 30 miniature peanut butter cups and divide them into three equal portions of 10 each.

If any cake layers are domed, level them with a serrated knife. Place one cake layer on a serving plate. Spread 1 cup of the peanut butter frosting evenly over the layer, then sprinkle one portion (10) of the chopped peanut butter cups over the frosting.

Place a second cake layer on top, spread another 1 cup of peanut butter frosting evenly, and sprinkle the second portion (10) of chopped peanut butter cups over that frosting.

Place the final cake layer on top (face-down, if you prefer the flattest top). Use the remaining peanut butter frosting to frost the top and sides of the cake, smoothing as desired. Refrigerate the frosted cake for at least 1 hour, until the frosting is set.

While the cake chills, make the chocolate ganache: place 8 ounces (226.8 g) finely chopped semisweet chocolate in a 4-cup measuring cup or heatproof bowl. Heat ¾ cup (178.5 ml) heavy cream in a small saucepan over medium heat until it just comes to a boil. Pour the hot cream over the chopped chocolate and let sit undisturbed for 2 minutes.

Whisk the chocolate and cream starting in the center and gradually working outward until the ganache is completely smooth. Set the ganache aside and whisk occasionally until it has thickened slightly but is still pourable.

If needed, transfer the ganache to a 2-cup measuring cup for easier pouring. Slowly pour the ganache into the center of the chilled cake, allowing it to spread outward and drip over the sides.

Immediately top the ganache-covered cake with the remaining portion (10) of chopped miniature peanut butter cups. Refrigerate the cake for at least 30 minutes to let the ganache set.

Keep the cake refrigerated; remove it about 20 minutes before serving.