Preheat oven to 350 degrees Fahrenheit.

Add cake mix, flour, salt, and lemon zest in a large mixing bowl. Whisk to combine ingredients until the lemon zest is blended well throughout the cake mix.

In a second large mixing bowl, combine ricotta cheese, softened butter, vanilla extract, lemon extract, and eggs. Fold ingredients together until they are well combined.

Add juice of one lemon to the bowl with the ricotta cheese mixture. Stir until the lemon juice is well incorporated.

Add cake mix and flour mixture to the bowl with the ricotta mixture in batches. Use a large spoon or spatula to fold the cake mix mixture into the ricotta mixture after each addition.

Add extra flour as needed, in 2 to 4 Tbsp increments, and work the flour into the ricotta cookie dough until a stiff dough forms.

Use a cookie scoop to scoop out about 1 Tbsp of ricotta cookie dough at a time. Shape the dough into a round, walnut-sized shape.

Place the cookie dough rounds about 2 inches apart on the cookie sheet(s).

Bake 8 to 10 minutes, or just until the edges of the cookies are golden brown. The cookies will continue to cook on the cookie sheet after it is removed from the oven.

Remove the lemon ricotta cookies from the oven. Let the cookies cool on the cookie sheet for 5 minutes, and then transfer the cookies to a cooling rack to cool completely.

Meanwhile, make the lemon icing. Add the confectioners sugar, vanilla extract, lemon extract, and lemon juice to a bowl. Stir until the ingredients are well blended and the icing is smooth.

Use a fork to drizzle the lemon icing over the ricotta cookies, or use the back of a spoon to smooth lemon icing over the top of each cookie. A piping bag can also be used to apply icing to the cookies.