1. In a large bowl, with a mixer on medium speed, beat 1 cup butter and sugar until smooth. Add whole egg and almond extract and beat until well blended. Add flour and baking powder; stir to mix, then beat until well blended.
2. Shape dough into 1-inch balls, flatten each slightly, and place about 1 inch apart on buttered 12- by 15-inch baking sheets.
3. In a small bowl, beat egg yolk with milk to blend. Brush cookies lightly with egg mixture; discard any remaining. Press an almond into the center of each cookie and sprinkle with about 1/8 teaspoon sesame seeds.
4. Bake cookies in a 325° regular or convection oven until lightly browned, 15 to 20 minutes; if baking two sheets at once in one oven, switch their positions halfway through baking. Let cookies cool on sheets for 5 minutes, then use a wide spatula to transfer to racks to cool completely.
Nutritional analysis per cookie.