Preheat oven to 300°F. Grease and flour an 8- or 9-inch square pan.

In a mixer fitted with a whisk attachment, beat the eggs at medium speed until fluffy and light yellow. Add sugars and mix to combine. Add remaining ingredients (melted coconut oil through salt), and mix to combine.

Pour the batter into a greased and floured 8-inch square pan. Bake in the preheated oven for 45 minutes, or until a toothpick inserted into the center of the pan comes out clean. Place the brownie pan on a cooling rack and let cool before slicing and dusting with powdered sugar.