Preheat the oven to 325F and line 2 baking sheets with silicone mats or parchment paper.
Beat the butter with the sweetener until well combined, then beat in the egg and vanilla extract until creamy. Beat in the ricotta and the zest
All at once, add the almond flour, coconut flour, baking powder, baking soda, and salt. Beat in until the dough comes together.
Roll the dough into 1 inch balls and place 2 inches apart on the prepared baking sheet. With the palm of your hand, press down to flatten slightly (they should still be rounded and about ¾ inch thick - this helps them crack less on the tops).
Bake 15 to 20 minutes, switching the pans partway through baking, until lightly browned. They will still be very soft. Remove and let cool completely on the pans.
In a medium bowl, whisk together the sweetener, cream, and vanilla extract. Whisk in the water, a little at a time, to thin it out. The glaze should be thin enough to dip the cookies.
Dip the top of each cookie in the glaze, turn right-side up, and shake the cookie slightly to even it out. (You can also spread the glaze on, and shake the cookie gently to even it out). Place on a cooling rack and add the sprinkles, if using. Let set 1 hour.