Spread bread cubes evenly onto a rimmed 18 by 13-inch baking sheet then bake in preheated oven until until nearly dried, tossing once halfway through, about 10 minutes total. Remove and let cool.
Reduce oven temperature to 300 degrees.
In a large mixing bowl whisk together brown sugar, granulated sugar, cinnamon and nutmeg (while breaking up brown sugar clumps with fingertips as needed).
Whisk in eggs and egg yolks until combined. Then blend in milk, heavy cream and vanilla extract until well combined.
Place bread cubes into an extra large mixing bowl, pour milk mixture over top then toss mixture with a rubber spatula to coat. Let rest until milk mixture has been absorbed, tossing occasionally, about 15 - 30 minutes.
Spread melted butter into a casserole dish (about 12 by 8-inch). Pour bread mixture into baking dish and spread evenly.
Bake in preheated 300 degree oven until center is set, about 50 - 65 minutes.
Let cool 10 minutes then cut into squares and serve with salted caramel sauce or vanilla sauce and whipped cream if desired.
Recipe source: Cooking Classy
Follow link HERE for Salted Caramel Sauce. Nutrition does not include toppings.