Prepare the Dough:

1. Preheat the Oven: Preheat your oven to 350°F (175°C) and line two baking sheets with parchment paper.
2. Mix the Wet Ingredients: In a large mixing bowl, cream together the softened butter and peanut butter until smooth and fluffy. Add the granulated sugar, brown sugar, eggs, and vanilla extract, and mix until combined.
3. Add the Dry Ingredients: In a separate bowl, whisk together the all-purpose flour, baking soda, and salt. Gradually add the dry ingredients to the wet ingredients, mixing just until combined.
4. Chill the Dough (Optional): If you have time, chill the cookie dough in the refrigerator for 30 minutes. This step helps the dough firm up, making it easier to roll into balls and helps prevent the cookies from spreading too much while baking.

Shape the Cookies:

5. Roll the Dough into Balls: Using a cookie scoop or spoon, roll the dough into 1-inch balls. Roll each dough ball in the extra granulated sugar (¼ cup) to coat.
6. Place on Baking Sheets: Place the dough balls on the prepared baking sheets, spacing them about 2 inches apart. Press each ball slightly to flatten it.
7. Insert the Peanut Butter Cups: Gently press a mini peanut butter cup into the center of each flattened cookie dough ball, slightly pushing it into the dough without squashing it.

Bake the Cookies:

8. Bake the Cookies: Bake the cookies in the preheated oven for 10-12 minutes, or until the edges are golden brown but the center is still soft.
9. Cool the Cookies: Remove the cookies from the oven and let them cool on the baking sheets for 5 minutes before transferring them to a wire rack to cool completely.