Heat your oven to 350 degrees Fahrenheit. Mix all of the ingredients except the margarine together. Cut the cold margarine in pieces and add to the ingredients. You can use a pastry cutter to mix in the margarine, I like to use my hands. Mix everything until the margarine is fully incorporated with the rest of the ingredients and a soft dough is formed. Put the dough into a 7x9 inch pan and press and flatten it in. Bake it for about 30 minutes, or until the top is golden and the edges are browned.