Cinnamon French Toast Casserole

I found this recipe via Pinterest and made it for Christmas morning.
I prepped the casserole on the night of December 23rd and cooked it on Christmas morning -- it held up just fine, so prepping ahead is a plus!

ingredients
1 loaf challah bread
8 whole eggs
2C half-and-half
1/2C heavy whipping cream
3/4C sugar
2 tbs vanilla
1/2C all-purpose flour
1/2C brown sugar
1 tsp cinnamon
1/4 tsp salt
1 stick cold butter, cubed

directions

1. Grease a 9x13 pan (I used Pyrex).
2. Tear bread into chunks and put into pan.
3. In a large bowl, mix together eggs, half-and-half, cream, sugar, vanilla.
4. Pour mixture evenly over bread.
5. Cover pan and refrigerate over night (or nights).
6. In another bowl, mix together flour, brown sugar, cinnamon, and salt.
7. Using your (CLEAN!) hands, crumble the butter into the mixture until it resembles small pebbles.
8. Place mixture in a bag and refrigerate until ready to use.
9. When you are ready to eat: preheat oven to 350 degrees.
10. Take out your 9x13 pan and sprinkle the bagged crumb mixture over the top of the bread.
11. Bake for 1 hour, or less if you like soggier french toast.
12. Serve with butter or syrup or both!
13. Enjoy!