Preheat your oven to 350°F (175°C). Line two baking sheets with parchment or a silicone mat—this prevents sticking and gives you perfect bottoms every time.

In a large bowl, beat the softened butter, peanut butter, granulated sugar, and brown sugar until light and fluffy (about 2–3 minutes). You’ll see pale ribbons form—that’s our cue.

Scrape down the bowl, then add the egg, extra yolk, and vanilla. Mix on medium speed until just combined, taking care not to overbeat.

In a separate bowl, whisk together flour, baking soda, and salt. This ensures even leavening and a soft crumb.

Gradually fold the dry mix into the wet with a flexible spatula, stopping when no streaks of flour remain. The dough should be slightly tacky but hold its shape.

Cover the bowl with plastic wrap and chill the dough for 20–30 minutes. Chilling firms the dough so your cookies don’t spread into one another like pancake batter.

While the dough chills, stir together the filling peanut butter, powdered sugar, and a pinch of salt until smooth. If it’s too thick, add a teaspoon of milk or cream.

Scoop 2-tablespoon portions of dough, roll lightly into balls, then flatten each one into a thick disc. Place 1 teaspoon of filling in the center, then bring the edges up and pinch to seal. Roll again into a tidy ball—seal is key.

Arrange dough balls 2 inches apart and bake for 10–12 minutes, until edges look set but centers still seem a touch soft. They’ll firm as they cool.

Let cookies rest 5 minutes on the sheet before transferring to a wire rack. Trust me—fresh from the oven is the best, but they stay soft for days if stored right.