Preheat oven to 375°F (190°C). Line a baking sheet with parchment paper.
In a medium bowl, combine flour, baking powder, and salt. Set aside.
In a large bowl, beat the butter and sugar until light and fluffy. Add the ricotta cheese, egg, lemon zest, and lemon juice. Beat to combine.
Stir in the dry ingredients until just combined.
Drop dough by rounded tablespoons onto the prepared baking sheet. Bake for 15 minutes, or until slightly golden at the edges.
Remove from oven and let cookies cool on the baking sheet for 20 minutes.
For the glaze, combine powdered sugar and lemon juice in a small bowl and stir until smooth. Spoon about ½ teaspoon onto each cookie and use the back of the spoon to gently spread.
Let the glaze harden for about 2 hours. Store in an airtight container.