Step 1: Preheat and prepare the pan
Preheat your oven to 350°F (175°C). Generously grease a Bundt pan with butter and lightly dust with flour, tapping out excess.

Step 2: Combine dry ingredients
In a medium bowl, whisk together the all-purpose flour, baking powder, baking soda, and salt until evenly blended.

Step 3: Cream the butter and sugar
Using a stand mixer with a paddle attachment or a hand mixer, beat together the room-temperature butter and granulated sugar until light and fluffy — about 4–5 minutes.

Step 4: Add the eggs
Add the eggs, one at a time, beating well after each addition. This helps incorporate air into the batter, yielding a fluffier texture.

Step 5: Alternate adding buttermilk and flour mixture
Add half of the flour mixture to the batter and blend until just combined. Then add half of the buttermilk and blend again. Repeat until all the flour and buttermilk are incorporated, adding vanilla extract last.

Step 6: Bake the Bundt Cake
Pour the batter evenly into your prepared Bundt pan. Bake in your preheated 350°F (175°C) oven for 40–45 minutes or until a toothpick inserted in the center comes out clean.

Allow the Bundt to cool in the pan for 10 minutes, then invert it onto a wire rack to cool completely.

Step 7: Prepare frosting
While the Bundt cools, combine the creamy peanut butter and room-temperature butter in a large bowl.
Add the powdered sugar, heavy cream (one tablespoon at a time), vanilla extract, and a pinch of salt.
Beat until smooth, creamy, and easily spreadable.

Step 8: Prepare ganache
Heating heavy cream in a small saucepan over medium heat until it starts to steam (but not boil).
Remove from heat and add the chopped chocolate.
Let sit for 5 minutes, then add vanilla extract and slowly stir until smooth and glossy.

Step 9: Assemble
Once the Bundt is cooled completely, spoon frosting over the top, allowing it to slowly cascade down the sides.
Drizzle with warm chocolate ganache in a zig-zag pattern.
Lastly, sprinkle chopped Butterfinger candy over the frosting.