Heat the oven to 180°C/350°F and cover a large baking tray with parchment paper or use a Silpat cookie sheet. Prepare the tray before mixing so the dough can go straight onto a nonstick surface.

Place the peanut butter, allulose, and egg in a large bowl, then stir firmly until no streaks of egg remain. The finished dough should look glossy and evenly blended, with no separated oil around the bowl.

Roll the dough into 12 balls and arrange them on the prepared tray, then flatten each into a round cookie and press a criss-cross with two forks. Dip the fork tines in cool water between presses if the dough begins to cling to the metal.

Bake for 10 to 12 minutes, until the cookie edges show a light golden ring. The centers may still feel soft, which keeps them from becoming dry once they cool.

Leave the cookies on the baking sheet until completely cooled before moving them. They firm up as the warm peanut butter and egg structure settles, making them easier to lift without breaking.