Preheat and prep: Heat the oven to 350°F (175°C). Line two baking sheets with parchment paper or silicone mats.
Cream the fats and sugars: In a large bowl, beat 1/2 cup unsalted butter, 3/4 cup creamy peanut butter, 1/2 cup granulated sugar, and 1/2 cup packed brown sugar until light and fluffy, about 2 minutes. This builds air for a tender cookie.
Add wet ingredients: Beat in 1 large egg, 2 teaspoons vanilla extract, and 1 tablespoon milk until smooth.
Scrape the bowl so everything mixes evenly.
Combine dry ingredients: In a separate bowl, whisk 1 1/3 cups all-purpose flour, 1/2 teaspoon baking soda, 1/2 teaspoon baking powder, and 1/4 teaspoon fine salt.
Mix the dough: Add the dry mixture to the wet ingredients in two additions. Mix on low just until combined. The dough should be soft and slightly sticky but hold its shape.
Optional add-ins: Fold in 1/2 cup mini chocolate chips or 1/3 cup chopped peanuts if you like extra texture.
Scoop and shape: Use a tablespoon or a #40 cookie scoop to portion the dough into balls.
Place them 2 inches apart on the baking sheets.
Press a crisscross: For that classic look, lightly flatten each ball with a fork in a crosshatch pattern. Don’t press too thin—aim for about 1/2 inch thick to keep centers soft.
Bake: Bake 8–10 minutes, rotating the pans halfway. The edges should look set, and the centers should look slightly underbaked.
They’ll firm up as they cool.
Finish and cool: Let cookies rest on the sheet for 5 minutes, then transfer to a wire rack. If you like a sweet-salty finish, sprinkle a little flaky sea salt on top while warm.