Instructions:
- Preheat oven to 350°F (175°C). Line baking sheets with parchment paper.
- In a medium bowl, whisk together the flour, baking soda, and salt. Set aside.
- In the large bowl, beat the softened butter, peanut butter, brown sugar, and granulated sugar together using an electric mixer until the mixture is light and fluffy (about 2–3 minutes).
- Beat in the egg and vanilla extract until just combined. Scrape down the sides of the bowl with a spatula.
- Gradually add the dry ingredient mixture to the wet mixture, mixing on low speed until just incorporated. Do not overmix.
- Cover the dough and chill for 30 minutes if the dough seems too soft to prevent excessive spreading.
- Roll dough into uniform balls (about 1.5 tablespoons each). Place 2 inches apart on prepared baking sheets.
- Use a fork to gently press down on each ball, creating a classic criss-cross pattern. Lightly dust the fork with flour if sticking occurs.
- Bake for 10–12 minutes. The edges should be set and lightly golden, but the centres may still appear slightly soft.
- Let cookies cool on the baking sheet for 5 minutes to firm up before transferring them to a wire rack to cool completely.