3/4 cup peanut butter or other nut butter
1/2 cup powdered sugar
1 teaspoon pumpkin spice mix, plus more to taste
1 pound good-quality dark chocolate or milk chocolate, chopped if purchased as a block
1/2 cup pumpkin butter, optional
→ For detailed step-by-step instructions with photos: How To Make Chocolate Peanut Butter Cups
Combine the peanut butter, powdered sugar, and pumpkin spice mix in the bowl of a food processor. Pulse 15 to 20 times until the mixture is dry and crumbly. It should hold together in a ball when pressed and feel moldable but no longer creamy; add more powdered sugar if needed. Taste and add more pumpkin spice in 1/2 teaspoon portions to taste.
Transfer the peanut butter filling to a clean bowl, cover, and keep chilled in the refrigerator until ready to use.
Melt 1/3 of the chocolate in a double-boiler or a heat-proof bowl set over a saucepan of simmering water. Let the chocolate stand without stirring until nearly melted, then stir until smooth. Transfer the melted chocolate to your workspace.
While the chocolate is melting, arrange 24 muffin cup liners on a baking sheet. Once the chocolate has melted, use a spoon to scoop up a small amount of chocolate and drizzle it into the cup liners. Use the back of the spoon to gently smooth the chocolate into a thin layer (roughly 1/8-inch thick, but no need to get exact about it!) on the bottom of the cup. Repeat with all the remaining liners.
Let the chocolate set until hardened. If your house is chilly, the first cups will already be setting by the time you finish the last ones. To speed things along, you can place the cups in the fridge for a few minutes. Wait until the chocolate is firm before continuing with the next steps.
While the chocolate is setting, begin preparing the filling. Scoop up 2 teaspoons of filling and shape them into thick disks with your fingers. The disks should be nearly the diameter of the cup with just a little space left around the edge. Once the chocolate has set, place one disk of filling in the middle of each cup. Dollop about a teaspoon of pumpkin butter over the top of each disk.
Melt the remaining chocolate over a double-broiler or in a heat-proof bowl set over a saucepan of simmering water. Let the chocolate stand without stirring until nearly melted, then stir until smooth. Transfer the melted chocolate to your workspace.
Scoop a generous spoonful of chocolate over the peanut butter filling in each cup. Use the back of the spoon to gently spread the chocolate around the filling and smooth the top. The chocolate should completely cover the filling. If the chocolate starts to thicken too much to easily work with, set