Step 1: Preheat your oven to 350°F (175°C). Line a baking sheet with parchment paper.
Step 2: In a large bowl, cream together the softened butter, creamy peanut butter, granulated sugar, and brown sugar until light and fluffy.
Step 3: Beat in the egg and vanilla extract until well combined, scraping down the sides of the bowl as needed.
Step 4: In a separate medium bowl, whisk together the all-purpose flour, baking soda, and salt.
Step 5: Gradually add the dry ingredients to the wet ingredients, mixing on low speed until just combined. Do not overmix.
Step 6: Roll the dough into small, 1-inch balls. Place them about 1-2 inches apart on the prepared baking sheet.
Step 7: Gently press each cookie ball with the tines of a fork in a criss-cross pattern. This helps them flatten and bake evenly.
Step 8: Bake for 8-10 minutes, or until the edges are lightly golden and the centers are just set. They may still look slightly soft in the middle.
Step 9: Remove from the oven and let the cookies cool on the baking sheet for 5 minutes before transferring them to a wire rack to cool completely. Enjoy!