Preheat the oven to 375 degrees and prepare a cookie sheet with parchment paper or a Silpat.
In a medium bowl, combine the dry ingredients: Flour, baking powder, cornstarch and salt.
In the bowl of an electric mixer (or a large bowl for a hand mixer) beat the butter and sugar until light and fluffy.
Add each egg in one at a time.
Add the ricotta cheese, lemon juice, vanilla, and lemon zest.
Beat on high until combined.
Fold in the dry ingredients into the butter mixture.
Using a cookie scooper, scoop balls of dough onto the cookie sheet. Bake 9 cookies at a time.
Bake for 12 minutes or until cookies have risen.
Let them cool while you make the glaze.
To make the glaze, add all the ingredients into a small bowl and mix with a fork until combined.
Add more lemon juice if it's too thick or a tablespoon of powdered sugar if it's too thin. You want a nice glaze consistency.
Drizzle over the top of each cookie.