Cream butter and sugar together in a large mixing bowl until light in color, about 1-2 minutes. Add egg and milk; stir to combine. Add remaining dry ingredients (except apple) and stir just until combined. Gently fold in the apples. Drop by heaping tablespoons onto a greased baking sheet.
Bake at 400 for about 10-12 min or until tops don’t look wet anymore.
To make the glaze, whisk together all glaze ingredients in a small bowl. When the cookies have cooled for a few minutes, drizzle each cookie with glaze.