Pour the milk into a saucepan over medium heat and scald it. (Heat until a skin forms on the top - almost boiling.)
8 c. whole milk
In a separate bowl, beat the eggs. Add the sugars, flour, and salt. Beat well.
12 large eggs, 1 c. white sugar, 3/4 - 1 c. brown sugar, 1 Tbsp. (heaping full) all-purpose flour, 1/4 tsp. salt
Add about a cup of the hot milk to the egg mixture to temper it. Slowly add the egg mixture to the milk, whisking as you are pouring it in. Remove from the heat and add the vanilla.
1 tsp. vanilla
Immediately pour the custard mixture into a 9 x 13" metal pan. Do not use a glass pan!
Sprinkle the top of the custard with cinnamon and nutmeg, as desired.
cinnamon and nutmeg, to taste
Bake the custard for 3 minutes at 475°. Turn off the heat and let the custard sit in the oven until the oven is cool. (At least 2 hours.)
Remove the custard from the oven and refrigerate for up to a week.
Notes
The whole milk can be replaced with 2% milk. And I have even used 7 cups of 1% milk with 1 cup of heavy cream. Although, it seems whole milk still works the best.*Nutrition facts are an estimate.