Preheat the oven to 375 degrees F. Line a baking sheet with parchment or a silicone mat.
With an electric mixer, beat together the peanut butter, brown sugar and egg until well combined. Stir in the chocolate chips with a wooden spoon.
Lightly wet your hands and form the mixture into 12 balls. Place the balls about 1 inch apart on the baking sheet. Lightly wet the tines of a fork and press a criss-cross pattern into the top of each cookie. Lightly sprinkle them with flaky sea salt.
Bake until just starting to brown, 12 to 15 minutes. Let sit for 5 minutes on the baking sheet, then remove to a rack to cool completely before eating.