To make the cookies: Preheat the oven to 350ºF. Line 2 baking sheets with parchment paper or nonstick silicone liners.

Combine the flour, baking soda and salt in a small bowl.

Combine the butter and granulated sugar in the bowl of a stand mixer fitted with the paddle attachment and beat on high speed until light and fluffy. Add the ricotta, eggs and vanilla extract, and beat until thoroughly incorporated. Reduce the mixer speed to low and add the flour mixture, beating until just combined. Refrigerate dough if not baking right away.

Drop the dough by the teaspoon onto the baking sheets, spacing the cookies two inches apart. Bake, rotating and switching the position of the sheets halfway through the baking, until the cookies spread and become golden around the edges, about 12 minutes. Cool on the baking sheets for 5 minutes, then remove the cookies with an offset spatula to racks and cool completely.

To make the icing: Combine the confectioners' sugar, milk and butter in a medium bowl and whisk together until smooth. Drizzle the icing onto the cooled cookies using a teaspoon, holding it perpendicular to the cookie and letting the icing drip from the tip of the spoon.