Let’s break down the process into easy-to-follow steps.

1. Prepare Pan and Preheat Oven: Preheat the oven to 350°F (175°C). Spray a 9-inch round cake pan with nonstick baking spray. Line the bottom of the pan with parchment paper and spray with nonstick baking spray. Set the pan aside.

2. Whisk Dry Ingredients: Sift the flour, sugar, cocoa powder, baking soda, baking powder, and salt in a large bowl; whisk to combine.

3. Whisk Wet Ingredients: In a separate large bowl, whisk together the buttermilk, oil, egg, and vanilla.

4. Combine Wet and Dry Ingredients: Gradually add the flour mixture to the buttermilk mixture, and whisk until well combined.

5. Add Coffee: Add the coffee and whisk just until evenly incorporated.

6. Bake: Transfer the batter to the prepared pan and bake for 28 to 32 minutes, until a toothpick comes out clean.

7. Cool: Let the cake cool in the pan for 15 minutes. Invert onto a cooling rack to cool completely, 1 hour.

8. Make Chocolate Ganache: In a 4-cup heat-proof liquid measuring cup with a spout, combine the chocolate chips and 1 tablespoon butter. In a small saucepan, bring the heavy cream and light corn syrup to a low simmer over medium-low heat. Pour the cream mixture over the chocolate mixture and let it stand for 2 minutes. Stir until very smooth. Set aside until cooled slightly, but still pourable (about 105°F / 40°C), 2 to 5 minutes.

9. Prepare for Ganache Pour: While the chocolate ganache is cooling, set the cake, still on the wire rack, in a rimmed baking sheet.

10. Pour Ganache: Once the ganache has cooled slightly, pour it over the cake, making sure to completely cover the top and sides, letting any excess run off into the rimmed baking sheet. Smooth the top of the cake using a large offset spatula.

11. Make Peanut Butter Swirl (Optional): While the chocolate ganache is cooling in Step 8, combine the peanut butter chips and butter in a small microwavable bowl. Microwave on high until the mixture is melted and smooth, 30 seconds, stopping to stir after 15 seconds. Transfer the peanut butter mixture to a small Ziploc bag with a 1/4-inch hole cut in the corner. Immediately after covering the cake with warm ganache in Step 10, pipe 6 equally spaced lines of the peanut butter mixture across the top of the cake. Using a paring knife or skewer, drag the tip through the peanut butter and ganache in 7 evenly spaced lines perpendicular to the piped peanut butter, alternating the direction of each line.

12. Chill: Immediately transfer the cake to the refrigerator to harden the ganache, 30 minutes.

13. Serve: Using 2 large spatulas, carefully transfer the cake to a serving platter. Serve slightly chilled or at room temperature.

These are clear and detailed instructions.