Blend the cottage cheese in a small blender or food processor until completely smooth.
In a large bowl, beat the butter and sweetener until creamy. Add the blended cottage cheese, egg yolk, vanilla, and almond extract, and beat until smooth.
Whisk together the almond flour, baking powder, xanthan gum, and salt, then stir into the wet mixture until a soft dough forms. Chill for 30 minutes.
Preheat the oven to 350°F and line a baking sheet with parchment paper. Roll the dough into 1 1/2 tbsp balls and flatten each one into a smooth round about 1/2 inch thick.
Bake for 11 to 13 minutes, until the edges are just barely golden. Cool on the baking sheet for 15 minutes, then move to a wire rack and cool completely.
Beat the cream cheese and butter until fluffy. Add the powdered sweetener, vanilla, and heavy cream, and beat for 2 minutes until smooth and spreadable.
Spread a thick layer of frosting over each cooled cookie and top with sprinkles. Store in the fridge.