Preheat the oven to 350°F (177°C). Line a 12-cup muffin pan with cupcake liners. This recipe yields about 15 cupcakes, so line a second muffin pan with 3 more liners or bake in batches.

Whisk the flour, cocoa powder, baking soda, baking powder, and salt together in a medium bowl. Set aside. In a large bowl, preferably with a pour spout, whisk the oil, sugar, egg, vanilla extract, and buttermilk together until combined. Pour the dry ingredients into the wet ingredients, add the hot coffee/water, and whisk until the batter is completely combined. The batter is thin.

Pour/spoon the batter into the liners, filling only 2/3 full to avoid spilling over the sides. You should have enough batter for 15 cupcakes.

Bake for 20–22 minutes, or until a toothpick inserted in the center comes out clean.

Allow the cupcakes to cool in the pan for 10 minutes, then transfer to a wire rack to cool completely. Cupcakes must be completely cooled—and even chilled for 20–30 minutes in the refrigerator if they’re particularly sticky on top—before assembling.

Using a handheld or stand mixer fitted with a paddle attachment, beat the softened butter on medium speed for 1 minute until completely smooth and creamy. Add the peanut butter and beat on medium-high speed until completely combined. Add the confectioners’ sugar, cream, vanilla extract, and salt. Beat on low speed for about 20 seconds, then increase to high speed and beat for 1 minute.

Using a sharp knife, cut a circle into the center of the cooled cupcakes to create a little pocket about 1 inch deep. The piece you removed will be roughly cone-shaped. Spoon cooled salted caramel sauce inside each carved-out cupcake; use however much will fit. (Usually you can fit between 1–2 teaspoons of caramel in each.) Slice/tear off the pointed end of the “cone” piece of cupcake you removed, and gently press the round piece back on top of the filling. See my How to Fill Cupcakes post if you need extra visuals or help with this step.

Pipe or spread the peanut butter frosting on top of the cupcakes. I used a Wilton #1A round tip. Top with a drizzle of caramel sauce and chopped Snickers bars.

Serve immediately or store covered in the refrigerator for up to 1 day before serving. (Bring to room temperature before serving.) Cover and store leftover cupcakes in the refrigerator for up to 3 days. I recommend a cupcake carrier for storing and transporting decorated cupcakes.