Martha Stewart's Crumb Cake

Preheat oven to 325°F. Place rack in the center of the oven. Prepare a 9-by-12 1/2-inch baking pan by spraying it lightly with pan spray.

In a small bowl, whisk together the egg, milk, oil and vanilla. Set aside. In a medium bowl, sift together 1 1/2 cups flour, sugar, baking powder and salt. Fold the egg mixture into the dry ingredients. Mix well.

Spread the batter evenly into the prepared pan and set aside. In another bowl, combine the remaining 2 1/2 cups of flour, brown sugar and cinnamon. Pour the melted butter over the mixture and combine until large crumbs form. Sprinkle the crumbs over the batter.

Bake for 35-40 minutes (rotating halfway through) or until the cakes tests done.

Transfer to wire rack to cool. Dust with powdered sugar (optional). Cut into 3-inch squares (or whatever size). Store in an airtight container for up to 3 days.