Heat oven to 400 degrees f and line baking sheets with parchment paper. In a large bowl, with an electric mixer cream the butter, sugar, and almond extract. In a separate bowl mix the dry ingredients: the flour, baking powder, and salt. Add the flour mixture 2 Tablespoons at a time to the butter mixture until completely combined (important!!)
Roll cookie dough into small 1-inch balls and flatten slightly. They should look like a thick checker. Cook for 7 minutes (they will not look done) at 400 degrees on a parchment lined pan. Cool cookies until they are just warm and place a few almond slices on top of each cookie.
For the glaze: Combine powdered sugar, almond extract, and water. Drizzle a spoonful of glaze on top of the almonds and cookie.