Grease a 13x9 inch deep sided casserole dish. Set a side.
Cut up a loaf of French bread into 1 inch sized cubes. Place in prepared casserole dish.
Beat together eggs in a large mixing bowl.
Add heavy cream, milk, rum, brown sugar, salt, cinnamon, nutmeg and vanilla extract. Whisk to combine all the ingredients.
Pour egg mixture over the cubed French bread in casserole dish. Use your hand to push bread cubes down into the egg mixture saturating all the cubed pieces of bread.
Cover casserole dish with foil or plastic wrap and refrigerate overnight.
In the morning take casserole dish out of the fridge and allow it to sit on the counter, covered, for 1 hour.
Preheat oven to 350℉.
In a large bowl combine Frosted Flakes, melted butter and salt.
Remove foil from casserole dish.
Spread buttered cereal evenly over the egg soaked bread cubes in the casserole dish.
Bake for 60-65 minutes until cereal is toasted golden brown and casserole is heated through.
Serve with your favorite French toast toppings; maple syrup, chopped nuts, fresh fruit, whipped cream.