In a mixing bowl whisk together flour, baking powder and salt for 20 seconds, set aside.
In the bowl of an electric stand mixer fitted with the paddle attachment whip together butter, granulated sugar and lemon zest until pale and fluffy (scrape down sides and bottom of bowl occasionally throughout entire mixing process).
Mix in ricotta and vanilla extract then blend in eggs one at a time. Set mixer on low speed and slowly add in flour mixture and mix just until combined. Cover bowl with plastic wrap and chill 2 hours or up to 2 days. Preheat oven to 350 degrees during last 20 minutes of dough chilling.
Scoop chilled dough out 1 Tbsp at a time and shape into balls (if it's too sticky just drop onto sheet using two spoons), drop onto a baking sheet lined with parchment paper (don't use dark baking sheets).
Bake in preheated oven until set, 12 - 14 minutes (bottoms will be lightly golden brown). Cool on baking sheet several minutes then transfer to a wire rack to cool completely.
Once cool spoon icing over cookies and return to wire rack, immediately add sprinkles if using.
Allow icing to set at room temperature. Store in an airtight container preferably in a single layer and preferably store in the fridge (bring to room temperature before serving).
For the glaze:
In a mixing bowl whisk together powdered sugar, melted butter, lemon juice or almond extract, vanilla and 4 Tbsp milk until smooth.
Add in more milk 1 tsp at a time to thin as needed (you don't want it to be very thin, it should be quite a bit thicker than a doughnut glaze).
*Scoop flour directly from container using measuring cup and level top using a butter knife. Don't whisk or sift before measuring and don't spoon into a cup. The best option is to use a kitchen scale, I highly recommend investing in one if you don't already have one. I always use mine when baking.
**Cookies previously listed using 2 tsp baking soda, but a few have had issues with cookies rising so recipe has been improved to use baking powder instead.