In a mixing bowl, whisk together the flour, baking powder, and salt for about 20 seconds. Set this mixture aside.

In the bowl of an electric stand mixer, whip together the room-temperature butter, granulated sugar, and lemon zest until the mixture becomes pale and fluffy.

Add in the ricotta and vanilla extract, then blend in the eggs one at a time, making sure each one is well incorporated.

Set the mixer on low speed and slowly mix in the flour mixture, combining just until everything is mixed together well.

Cover the bowl with plastic wrap and chill the dough in the refrigerator for 2 hours or up to 2 days for the best flavor and texture.

Preheat your oven to 350°F (175°C) during the last 20 minutes of chilling.

Once the dough is chilled, scoop out 1 tablespoon at a time and shape it into balls. Place them onto a baking sheet lined with parchment paper, spacing them out appropriately.

Bake in the preheated oven for 12 to 14 minutes, or until the cookies are set and lightly golden brown on the edges.

Let them cool on the baking sheet for several minutes, then transfer the cookies to a wire rack to cool completely.

For the icing, whisk together the powdered sugar, melted butter, lemon juice, vanilla extract, and 4 tablespoons of milk until the mixture is smooth.

Add more milk if needed to reach your desired icing thickness.

Once the cookies have cooled down, spoon the icing over the top and allow it to set.