Preheat the oven to 350°F (175°C). Line two baking sheets with parchment paper or silicone baking mats.
In a medium bowl, whisk together the flour, baking powder, baking soda, and fine sea salt. Set aside.
2 cups all-purpose flour, 1 1/2 teaspoons baking powder, 1/2 teaspoon baking soda, 1/2 teaspoon fine sea salt
In a large mixing bowl, beat the softened butter and granulated sugar on medium speed for 2–3 minutes, until light and creamy.
1/2 cup unsalted butter, 1 cup granulated sugar
Beat in the egg until fully combined. Add the ricotta, vanilla extract, lemon zest, and lemon juice. Mix on medium speed until smooth and creamy; the mixture may look slightly curdled at first but will come together as you mix.
1 large egg, 1 cup whole milk ricotta cheese, 2 teaspoons pure vanilla extract, 1 tablespoon lemon zest, 2 tablespoons fresh lemon juice
With the mixer on low speed, gradually add the dry ingredient mixture. Mix just until no streaks of flour remain. Scrape down the bowl and give the batter a final stir by hand. The dough will be thick and sticky, like a very soft cake batter.
2 cups all-purpose flour, 1 1/2 teaspoons baking powder, 1/2 teaspoon baking soda, 1/2 teaspoon fine sea salt
Using a small cookie scoop or a tablespoon, scoop heaping tablespoon portions of dough onto the prepared baking sheets, spacing them about 2 inches apart. If needed, lightly grease the scoop or your fingers to help release and tidy the tops.
Bake one sheet at a time for 11–14 minutes, rotating the pan halfway through. The cookies are done when the tops look set and no longer shiny, the edges are just barely golden, and the bottoms are lightly golden but not dark. Do not overbake; they should remain soft.
Let the cookies cool on the baking sheet for 5 minutes, then transfer them to a wire rack to cool completely before glazing.
In a medium bowl, whisk together the powdered sugar, 2 tablespoons of lemon juice, and vanilla extract (if using). Add more lemon juice a teaspoon at a time, and a teaspoon or so of milk or cream if needed, until you have a smooth, thick-yet-pourable glaze that slowly runs off the spoon but still clings.
1 1/2 cups powdered sugar, 2-3 tablespoons fresh lemon juice, 1-2 teaspoons milk or heavy cream, 1/2 teaspoon pure vanilla extract
Place parchment or wax paper under the cooling rack for easy cleanup. Spoon or drizzle about 1 teaspoon of glaze over each cooled cookie, gently nudging it toward the edges so it just begins to drip down the sides. Garnish with extra lemon zest or finely chopped candied lemon peel, if desired. Let the cookies sit at room temperature for 30–45 minutes, or until the glaze is set and no longer tacky.
2-3 tablespoons fresh lemon juice, extra lemon zest or finely chopped candied lemon peel