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 thoroughly.

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, about 30 seconds.

Fit a piping bag with a large open star tip such as the Ateco #824, and fill with dough. Holding the bag straight up and down, pipe the dough into tight circles, about 2 inches in diameter onto the prepared baking sheets.

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 for another 15 to 20 minutes. Remove and let cool completely on a wire rack.

In a heatproof bowl set over a bowl of barely simmering water, melt the chocolate and cocoa butter until smooth. Dip half of each cooled cookie into the melted chocolate and set on a waxed paper lined baking sheet. Sprinkle with sugar-free sprinkles, if desired, before the chocolate sets.