Instructions:
- Preheat oven to 375°F (190°C). Line baking sheets with parchment paper.
- In a medium bowl, whisk together the flour, baking soda, and salt. Set aside.
- In a large mixing bowl, beat the softened butter, peanut butter, granulated sugar, and brown sugar until light and fluffy (about 2-3 minutes).
- Beat in the egg until just combined, then stir in the vanilla extract. Scrape down the sides of the bowl.
- Gradually add the dry ingredients to the wet ingredients, mixing on low speed until just combined. Do not overmix.
- Cover the dough and chill in the refrigerator for at least 30 minutes to prevent excessive spreading.
- Roll dough into uniform balls (about 1.5 tablespoons each) and place 2 inches apart on the prepared baking sheets.
- Flatten each ball lightly with the palm of your hand, then use a fork dipped lightly in granulated sugar to press a crisscross pattern onto the top of each cookie.
- Bake for 10–12 minutes, or until the edges are set and lightly golden, but the centres still look slightly soft.
- Let the cookies cool on the baking sheet for 5 minutes before transferring them to a wire rack to cool completely.