Preheat your oven to 350°F (175°C). Line baking sheets with parchment paper.
Drain the ricotta cheese in a fine-mesh sieve lined with cheesecloth or a coffee filter for at least 30 minutes. Press gently to remove excess liquid.
In a large bowl, whisk together the drained ricotta cheese and granulated sugar until smooth.
Beat in the eggs one at a time until fully incorporated. Mix in the vanilla extract, lemon zest, and lemon juice.
In a separate medium bowl, whisk together the gluten-free flour blend, baking powder, and salt.
Gradually add the dry ingredients to the wet ingredients, mixing on low speed until just combined. Do not overmix the batter.
Drop rounded tablespoons of batter onto the prepared baking sheets, spacing them about 2 inches apart. The batter will be soft.
Bake for 15 to 18 minutes, or until the edges are lightly golden and the centers are set.
Let the cookies cool on the baking sheet for 5 minutes before transferring them to a wire rack to cool completely.
While the cookies cool, prepare the glaze: Whisk together the powdered sugar and 1 tablespoon of lemon juice until smooth. Add more juice, a few drops at a time, if the glaze is too thick.
Drizzle the glaze over the cooled cookies. Allow the glaze to set before serving.
Notes
Draining the ricotta is crucial; excess moisture makes the cookies spread too much.
If your gluten-free flour blend does not contain xanthan gum, add 1/2 teaspoon to the dry ingredients.
Store leftover cookies in an airtight container at room temperature for up to 3 days.