packed light brown sugar
- Filling: Stir together the sugar and cinnamon; set aside.
- Cookies: Cream the butter and brown sugar until well blended with an electric mixer on medium speed.
- Add the eggs and vanilla; blend well.
- Combine the flour, baking powder, salt, and cinnamon; add to butter mixture and blend well.
- Turn dough out onto a sheet of waxed paper; spread into a 9x6-inch rectangle using a rubber spatula.
- Sprinkle the cinnamon-sugar to within 1 inch from the edges.
- Roll dough up jelly-roll style.
- Roll in remaining cinnamon-sugar; wrap dough tightly in plastic wrap.
- Refrigerate at least 4 hours.
- Preheat oven to 350°F.
- Slice dough 1/4-inch thick; place 2 inches apart onto parchment-lined cookie sheets.
- Bake for 8 minutes or until golden on top.
- Cool for 4 minutes on the cookie sheets, then remove to racks and cool completely.