1. Mix ﬂour, oats, and cinnamon in a large mixing bowl.
2. Melt margarine and brown sugar together in the microwave and add to the ﬂour-oat mixture.
3. Press half of this “dough” in an even layer into the bottom of a nine- by 13-inch pan.
4. Preheat oven to 350 degrees Fahrenheit.