Set oven racks in the upper and lower third positions. Preheat the oven to 350°F. Line two cookie sheets with parchment paper. In a medium bowl, beat the peanut butter, stevia, baking soda, and salt with a handheld electric mixer on medium speed, scraping down the sides if needed, until well combined, about 1 minute. Reduce the speed to low, add the egg and vanilla extract, and beat until combined.Shape the dough into 24 balls (scant 1 tablespoon each) and place 2 inches apart on the prepared cookie sheets. Using the tines of a fork, carefully flatten each ball, creating a crisscross pattern. (Dampen the fork with water if it sticks.)Bake, rotating the cookie sheets from top to bottom and from back to front halfway through, until the edges are just beginning to brown and the cookies are just set, 7 to 9 minutes. (Do not overbake; the cookies should not be browned.) Let cool for 10 minutes on the cookie sheet, then carefully transfer to a cooling rack to cool completely.In a small microwave-safe bowl, add the chocolate chips and microwave on high in 20-second increments, stirring after each, until melted, about 1 minute total. (Alternatively, gently melt in a double boiler or in the top of two saucepans set up in a double-boiler style.)Dip a dry fork into the chocolate, then drizzle the chocolate over the cookies. Sprinkle with sea salt. Serve 1 cookie per person.