Preheat oven to 350°F. Cover cookie sheets with parchment paper; set aside. Place the sesame seeds in a 9-inch pie plate or a baking dish. Bake for 8 to 10 minutes or until browned. Remove and cool. Increase oven temperature to 375°F.
In a medium microwave-safe bowl melt the butter and cool for 10 minutes. Stir in brown sugar, lemon peel, egg, sesame seeds, flour, and baking powder until combined (dough will be soft).
Drop dough by rounded measuring teaspoons 2 inches apart on prepared cookie sheets. Bake for 7 to 8 minutes or until browned. Let cool 1 minute on sheets. Remove and cool on wire racks.