In a food processor or blender, combine flour, sugar and butter until it achieves a cornmeal texture.
Add peanut butter and vanilla extract. Pulse until combined. Form into a large dough ball and knead until smooth.
Press into a disc between ⅛-¼" thick or roll between parchment paper on a cookie sheet. Using a fluted cookie cutter, cut close together.
Bake 12 minutes or until edges are slightly golden. Allow to cool 1 minute before transferring to a cooling rack.
Notes
Pulsing the ingredients rather than using a mixer allows you to use cold butter. This keeps the cookies from spreading and will ensure the cookies are light and crispy.
Don't overmix or over-knead the dough. Too much mixing and kneading will activate the gluten and make the cookies tough instead of crispy and light.
Instead of using a cookie cutter, use a knife to cut into squares.
To store, place cookies in an airtight container. They can be stored at room temperature for up to one week, refrigerated for up to 10 days, and frozen for up to three months.