Preheat the oven to 325F and line two baking sheets with silicone baking mats or parchment paper.
In a food processor, combine the almond flour, sweetener, and salt. Pulse to combine.
Cut the softened butter into chunks and add to the processor. Pulse until the mixture resembles coarse crumbs. Add the egg and vanilla and process until the dough clumps together in one big ball.
Fit a piping bag with a large open star tip such as the Ateco #826 or 828, and fill with dough. Holding the bag straight up and down, pipe the dough into tight circles, about 2 inches in diameter. Tip: It takes a bit to get the hang of this but if you mess up, just take that cookie dough and add it back into the bag to be re-piped.
Bake the cookies for about 18 to 20 minutes, until they are just golden brown around the edges. Remove and turn off the oven. Let the oven cool for about 15 minutes, then put the cookies back in to dry out and firm up, another 15 to 20 minutes or so. Remove and let cool completely.
In a heatproof bowl set over a bowl of barely simmering water, melt the chocolate and cocoa butter. Dip half of each cookie into the chocolate and set on a waxed paper lined baking sheet. Sprinkle with sugar-free sprinkles, if desired.