Preheat oven to 350°F (175°C). Line a baking sheet with parchment paper.
In a bowl, whisk together flour, baking soda, salt, and instant coffee powder.
In another bowl, beat butter, peanut butter, brown sugar, and granulated sugar until smooth.
Add the egg and vanilla extract, mixing until well combined.
Gradually stir in the dry ingredients until a dough forms.
Scoop tablespoon-sized portions onto the prepared baking sheet, spacing 2 inches apart.
Flatten each dough ball slightly with a fork, making the classic peanut butter cookie crisscross pattern.
Bake for 12 minutes, or until the edges are firm but the centers remain soft.
Let cookies cool on the baking sheet for 5 minutes, then transfer to a rack.
Eat immediately, or store in an airtight container for later (if they last that long).