Set your oven to 350°F (177°C) and prepare two large baking sheets by lining them with parchment paper or silicone mats.
Combine the peanut butter, the whisked egg, and maple syrup in a big bowl; stir thoroughly until the mixture thickens into a dough-like consistency.
Scoop out tablespoon-sized portions of dough onto the baking sheets, spacing each about 2 inches apart.
Gently press each scoop with your palm to form a thick round disk, leaving room for more flattening when you add the criss-cross fork pattern.
Use the tines of a fork to create a criss-cross design on each cookie's surface.
Bake the cookies for 10 minutes until they show slight cracks and appear dry on top.
Allow the cookies to cool completely on the baking sheets before transferring them off.