Break up one loaf of brioche bread into bite size pieces and set aside. Mix together next four ingredients in a large bowl. Toss in the bread pieces and mix until combined and soggy. Melt butter and add half to one large loaf pan (hang onto the rest). Pour bread mixture into 2 loaf pans. Drizzle that remaining melted butter on top and sprinkle with cinnamon sugar mix. Bake at 350, for 50-60 minutes.
To make cinnamon sugar topping: Add 1/2 cup sugar and 2 tablespoons cinnamon to bowl and mix with a whisk or fork. I use about 2 tablespoons in this recipe. Keep the extra in a small mason jar or shaker bottle for future french toast, muffins, or apple pie.
Note: I usually double this recipe because we are a big family. Also, it's a great little surprise to deliver to a friend, neighbor, teacher, or new mom. Party hack: Scoop mounds of baked bread pudding from your loaf pan and into mini jars for parties. Top them off with a dollop of whipped cream and a drizzle of store bought caramel sauce and they are to die for!