Preheat oven to 300°F and butter and flour an 8-inch square pan.
In a stand mixer fitted with the whisk attachment or a mixing bowl and a hand mixer, beat the eggs on medium speed until fluffy and light yellow.
Add both sugars and mix.
Add remaining ingredients, and mix to combine.
Pour batter into prepared pan and bake for 45 minutes. Check for doneness by inserting a toothpick into the center of the pan; it should come out clean. Remove to a wire rack to cool. Let cool before slicing and serving.