Preheat oven to 375°F (190°C). Line baking sheets with parchment.
Whisk flour, baking soda, and salt in a bowl. Set aside.
Beat butter, peanut butter, granulated sugar, and brown sugar until creamy. Add egg and vanilla; mix until combined.
Gradually add dry ingredients until just mixed. Scoop tablespoon-sized balls and roll in granulated sugar.
Place on sheet 2 inches apart and bake 8–10 minutes until edges set but centers still soft.
Immediately press a chocolate kiss into each cookie; let cool on pan for 5 minutes, then transfer to a rack.