Grease a 9x13 inch baking dish with melted salted butter. Spread 1/4 cup brown sugar mixed with 1 teaspoon cinnamon evenly over the bottom of the dish.

In a mixing bowl, whip the cream cheese until smooth. Add in the heavy cream and vanilla, mixing until fluffy.

Slice 1-inch slits at the top of each loaf of challah bread to create pockets, and fill each pocket with the cream cheese mixture.

In a separate bowl, whisk large eggs, whole milk, vanilla, and a pinch of kosher salt. Soak each piece of your filled bread in the egg mixture for a couple of minutes.

Arrange the soaked bread snugly in the baking dish. Pour any remaining egg mixture over the top, and sprinkle the rest of your cinnamon sugar blend on top.

Cover the baking dish with plastic wrap and let it chill in the fridge for at least 30 minutes, or overnight.

Preheat your oven to 375°F. In a small bowl, mix brown sugar, cinnamon, flour, and softened butter to create a crumbly topping. Sprinkle it over the soaked bread.

Bake the French toast covered with aluminum foil for 25 minutes. Uncover and bake for an additional 20-25 minutes until golden brown and crunchy.