This is adapted to be gfcf, I found original recipe on the blog A Path Made Straight.

1/3 cup butter (I use a gfcf margarine or coconut oil)
2 large eggs
3/4 cup brown sugar
1 1/2 teaspoons baking powder (gf)
1 1/2 teaspoons vanilla
1 teaspoon cinnamon
1/4 teaspoon nutmeg
1/4 teaspoon salt
1 cup milk plus 2 tablespoons (use your favorite substitute; soy, almond, rice)
3 cups whole oats (gf)
1/4 cup of flax meal
1/4 cup of millet seed

Melt butter and set aside. In a large bowl, beat eggs well, then add brown sugar, baking powder, vanilla, cinnamon, nutmeg and salt. Mix well until there there no lumps.

Whisk in butter and milk, then add oats, flax meal and millet.

Stir well, and pour into a greased 8×8 baking dish. Refrigerate overnight.

Bake, uncovered, at 350 for 30-35 minutes, or until set in the middle. Serve hot! (I double this for leftovers – it’s even better two or three days later! – so if you would like to as well, use a 9×13 baking dish, and the cooking time is the same.)