Pour the contents of a sweetened condensed milk can in a baking pan, place it inside of a larger one, pour water in the large pan to form a water bath; bake the covered sweetened condensed milk for 3 to 4 hours until golden brown and thick.
Add sweetened condensed milk in the dough, also add a yolk, cornstarch, and cream of tartar, which all help the cookie have the best chewy consistency.
Roll the cookie in cinnamon and sugar mixture before baking for a delicious aroma and taste. The cinnamon also offers a light crisp on the outside of the baked cookie.
Mix butter, cream cheese, the rest of the sweetened condensed milk can that you used to make the cookie dough, dulce de leche, and vanilla. It’s not overly sweet since there’s no powdered sugar in it.
Pipe a swirl of frosting on top of the cookie, then fill the space in the swirl with dulce de leche.