In a medium bowl, whisk together the flour, baking powder, and salt. Set aside.

Add the sugar to a mixing bowl. Grate the lemon zest directly over the sugar, then rub it in with your fingertips until fragrant.

Add the butter to the lemon sugar. Then using a stand mixer fitted with the paddle attachment, beat the butter and sugar until light and fluffy. (A hand held electric mixer can also be used.)

Beat in the egg until fully combined. Mix in the ricotta cheese and vanilla extract.

Gradually add the dry ingredients to the butter and ricotta mixture in two parts, mixing until smooth and well combined.

Cover the bowl with plastic wrap and refrigerate for at least 2 hours or overnight.

Preheat the oven to 350°F (180ºC) and line two large baking sheets with parchment paper. Roll tablespoons of dough into balls and place them 2 inches apart on the baking sheets. Bake for 10–12 minutes, or until the bottoms are golden brown. Transfer to a wire rack to cool completely.

Juice the lemon, strain it to remove pulp, and measure out the amount needed. Sift the powdered sugar into a small bowl, then stir in the lemon juice until smooth.

Use a teaspoon to spread the glaze over the cooled cookies. Add colored spinkles before the glaze sets. Allow the cookies to stand for about 30 minutes until the glaze hardens.