Lightly beat sugar and butter in a large bowl for 2 minutes using a medium/high electric mixer. Mix ricotta, egg, and 1 tsp almond essence. Add the flour mixture.
To make the glaze, mix powdered sugar, milk, and ½ teaspoon of almond essence in a small basin. Glaze the cooled cookie. Re-dry wire-rack. Add almond slices.
Almond Ricotta Cookies can be made ahead and refrigerated for a week or frozen for a month.