Step 1

Preheat your oven to 350°F and line a baking sheet with parchment paper or silicone baking mat.

Step 2

In a small bowl, whisk together peanut butter, melted butter, brown and granulated sugar, egg yolk, and vanilla until well-combined.

Step 3

Add flour, baking soda, and salt, and use a spoon to stir until just combined.

Step 4

Form cookie dough into a ball and place on prepared baking sheet. Use a fork to press crosshatch patterns over the dough until pressed to about 1/2-inch thick (the cookie will spread more as it bakes).

Step 5

Bake for 12 to 14 minutes, until the edges of the cookie are just beginning to darken and the top looks set. Cool on the baking sheet for at least 10 minutes so the cookie has time to firm up. Serve and enjoy!