I found it at Serena Bakes Simply from Scratch . I followed the directions except for the struesel. Instead of using a baggie, I mixed it in my bowl using my hands. I didn't want any of it getting stuck in the baggie.
Overnight Blueberry French Toast Bake With Struesel Topping
1 loaf French Bread, ripped or cut into cubes
1 1/2 c. blueberries (If frozen thaw and drain juice.)
7 whole eggs
2 1/2 c. whole milk
1/4 c. pure maple syrup
3 t. vanilla extract
1 t. cinnamon
1/4 c. flour
1/2 c. brown sugar
1 t. cinnamon
1/4 t. sea salt
1/2 c. cold butter, cut into 8 cubes
Grease a 9"x 13" baking dish.
Add 1/2 of French bread cubes and top with 3/4 cup blueberries to dish. Add remaining bread cubes and top with remaining 3/4 cup blueberries.
In a medium sized bowl combine eggs, milk, maple syrup, vanilla and cinnamon. Mix until thoroughly combined.
Pour egg mixture over the top of bread and blueberries. Cover tightly and refrigerate overnight.
In a gallon sized Ziploc bag add flour, brown sugar, cinnamon, and sea salt. Close tightly and use fingers to thoroughly combine ingredients. Add butter and re-close bag. Use fingers to combine butter and sugar mixture until it resembles pea sized pieces. If butter becomes soft mixture, it will re-harden overnight in the refrigerator. Place Ziploc bag in the refrigerator overnight.
In the morning, preheat oven to 350°.
Remove casserole and streusel topping from the refrigerator. Use fingers to crumble streusel topping over the top of the bread and blueberries.
Bake for 50 minutes or until top is lightly browned.
Serve plain or with additional butter and maple syrup.