Melt butter in the bottom of a 9- x 13-inch pan in the oven. Mix the rest of the ingredients in a blender, food processor or mixer. Pour into the hot buttered pan and bake for 15 to 20 minutes, until high bumps appear and the top is lightly browned.
To serve, cut into individual rectangle servings. Serve immediately with optional toppings.
Recipe Note: This recipe can be cut in half and baked in a smaller pan.