Preheat your oven to 350°F. Line a cookie sheet with parchment paper.
In a medium bowl, lightly whisk an egg, then add the sweetener. Mix with a rubber spatula, then whisk with a wire whisk until smooth.
Add the peanut butter and mix well using a rubber spatula. The mixture will be very thick.
Use a cookie scoop to measure 1.5 tablespoons of dough per cookie. Shape them with your hands into balls.
Arrange the dough balls on the prepared cookie sheet, 1-inch apart, and gently flatten them with your hands.
Gently press 6-7 chocolate chips onto the top of each cookie.
Bake the cookies until their edges are beginning to darken, about 15 minutes.
Cool the cookies in the pan for about 10 minutes. They will be too soft to remove from the pan at this point.
Use a spatula to gently remove the cookies to a cooling rack. Cool them to room temperature, about 30 more minutes. The cookies will be very soft initially but will harden and set as they cool and get a proper cookie texture.
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Notes
If your peanut butter is unsalted, add a bit of salt – try ¼ teaspoon. The peanut butter I use is quite salty, and the saltiness comes through in the cookies and enhances them.Mix the peanut butter well before using it. It's best to use a fresh jar. Natural peanut butter at the bottom of the jar tends to be too dry to bake with, even if you've mixed it well when you first opened the jar.It's fine to omit the chocolate chips, although they are fabulous in this recipe. If you do omit them, make the cookies pretty by using a fork to create a crisscross pattern. So after placing the dough balls on the cookie sheet, press on them with the backside of a fork, then rotate the fork 90 degrees and press again.It's important to let the cookies cool on the cooling rack and not in the pan. That’s when they get a proper cookie texture.