This cookie tastes like the white park of the best black and white cookie you've ever had mixed with the zingy tang of lemon. Topped with a vanilla glaze, it's even better!
Using an electric mixer, cream 2 sticks butter with sugar until fluffy, about 2 minutes. Add ricotta, lemon zest and 2 1/2 teaspoons vanilla and beat well. Beat in the eggs one at a time. Scrape the sides of the bowl down with a rubber spatula, then beat in flour, baking soda and salt. Cover dough and chill for at least 2 hours and up to a week.
Heat oven to 350 degrees and line several cookie sheets with parchment paper or nonstick liners. Shape tablespoons of dough into balls. Place 2 inches apart on baking sheets and bake until pale golden on the bottom, about 15 minutes. Let cool on wire racks.
Melt remaining tablespoon butter. Whisk confectioners’ sugar to break up any large lumps, then whisk in melted butter, lemon juice, remaining 1 1/2 teaspoons vanilla and enough milk to make a spreadable icing. Spread icing on cooled cookies, then let set for at least 20 minutes before serving.
