1. Preheat the Oven:
- Preheat your oven to 350°F (175°C). Grease a mini muffin tin or line it with paper liners.
2. Make the Cookie Dough:
- In a large bowl, beat the butter, granulated sugar, and brown sugar until creamy.
- Add the egg and vanilla extract and mix until smooth.
- In a separate bowl, whisk together the flour, baking soda, and salt. Gradually add the dry ingredients to the wet ingredients, mixing until just combined.
- Fold in the chocolate chips.
3. Form the Cookie Cups:
- Scoop about 1 tablespoon of cookie dough into each cavity of the mini muffin tin. Use your fingers or the back of a spoon to press the dough down and create a shallow well in the center.
4. Bake:
- Bake for 10-12 minutes, or until the edges are lightly golden. The centers will still look soft. Remove from the oven and use a small spoon or the end of a wooden spoon to press the centers down again, forming a cup shape. Let the cookie cups cool in the tin for 10 minutes before transferring to a wire rack.
5. Make the Peanut Butter Filling:
- In a small bowl, mix the peanut butter, powdered sugar, and softened butter until smooth and creamy.
6. Fill the Cookie Cups:
- Spoon or pipe the peanut butter filling into the cooled cookie cups.
7. Serve and Enjoy:
- Serve at room temperature or chilled. Store any leftovers in an airtight container at room temperature or in the fridge for up to 5 days.