Preheat your oven to 350°F (175°C). Line two large baking sheets with parchment paper or silicone baking mats. Ensure your butter, eggs, and ricotta are at room temperature so they blend smoothly.

In a large mixing bowl or stand mixer, beat the softened butter and granulated sugar on medium-high speed for 2–3 minutes until light and fluffy, scraping down the sides as needed. Add the ricotta cheese and beat for another 1–2 minutes until the mixture looks creamy and well combined.

Add the eggs one at a time, beating well after each addition. Mix in the vanilla extract and optional lemon zest (and lemon extract if using), until the batter is smooth and fragrant.

In a separate bowl, whisk together the flour, baking powder, and salt. With the mixer on low speed, gradually add the dry ingredients to the wet mixture in 2–3 additions. Mix just until the flour is mostly incorporated and no dry pockets remain; do not overmix. The dough will be thick but soft, like a very thick cake batter.

Using a small cookie scoop (about 1 tablespoon) or a rounded tablespoon, drop mounds of dough onto the prepared baking sheets, spacing them about 2 inches apart. The cookies will puff rather than spread a lot.

Bake one sheet at a time for 11–14 minutes, or until the tops are set and look dry, the bottoms are lightly golden, and the centers spring back gently when touched. Do not overbake; the tops should remain pale. Let the cookies cool on the baking sheet for 5 minutes, then transfer to a wire rack to cool completely before glazing.

In a medium bowl, whisk together the powdered sugar, vanilla extract, and 3 tablespoons of milk until smooth. If using, add lemon juice and a pinch of salt. Adjust the consistency as needed: add more milk, 1/2 tablespoon at a time, if too thick, or more powdered sugar if too thin. The glaze should cling to the cookie but slowly run down the sides.

Once the cookies are completely cool, dip the tops of each cookie into the glaze or spoon the glaze over the top. Place them back on the wire rack set over parchment to catch drips. Immediately top with colored nonpareil sprinkles if using, before the glaze sets. Let the cookies rest at room temperature for 30–45 minutes, or until the glaze is fully set and dry to the touch.

Serve the cookies once the glaze is set. Store fully cooled and glazed cookies in an airtight container at room temperature for 3–4 days, layering with parchment paper between layers to protect the glaze.