Preheat the oven to 350°F. Lightly grease a 9x13-inch baking dish and set aside.
In a large mixing bowl, mix eggs, oil, milk, and vanilla.
In a medium bowl, blend flour, sugar, baking powder, and salt.
Add the flour ingredients to the wet ingredients and mix well. Pour half the batter into the prepared baking dish.
In a medium bowl, combine brown sugar and cinnamon and mix well.
Sprinkle half of the cinnamon sugar on top of the batter. Carefully spread the remaining batter over the cinnamon-sugar layer. Sprinkle the remaining cinnamon-sugar mixture on top.
Drizzle the melted butter over the top, using more or less as desired.
Bake for 35-40 minutes, or until a toothpick inserted in the center comes out with a few moist crumbs, and serve warm.