Preheat the oven to 350ºF.
Spray an 8x8 baking dish with nonstick cooking spray or line with parchment paper.
In a bowl, stir together all ingredients just until combined. Pour into the prepared dish. The batter will be thick - you may need to use a spatula sprayed with cooking spray to spread it out evenly.
Bake in the preheated oven until the center looks just a bit gooey, but the edges are set, about 20 minutes. Remove from the oven and allow to cool before cutting into squares.
