In the bowl of an electric mixer, beat the sugar and butter until light and airy.
Add vanilla extract, lemon zest, and ricotta, and mix until incorporated. Mix in the egg.
Add the flour, salt, and baking soda, and mix until incorporated.
Once complete, move the dough to the refrigerator and let chill for 2 hours or overnight.
Preheat the oven to 350F and prepare baking sheets.
Using hands or a cookie scoop, shape dough into 1 ½-inch diameter balls and place on baking sheets with at least two inches of distance between balls. Bake for 15-20 minutes or until cookies become golden brown.
Once the cookies have cooled, whisk together the icing ingredients in a medium-sized bowl. Lightly spread icing over each cookie and top with sprinkles.