For the French toast, grease a 9x13" pan with butter.
Tear the bread into chunks, or cut into cubes, and distribute evenly in pan.
Whisk together the eggs, milk, cream, granulated sugar, brown sugar and vanilla. Pour evenly over bread.
Spread fruit over top. Cover the pan tightly and store in the fridge until needed, preferably overnight.
For topping: Mix the flour, brown sugar, cinnamon, salt and some nutmeg in a bowl. Stir together using a fork.
Add the butter and using a pastry blender, cut in the butter until the mixture resembles small pebbles. Add the nuts and store in a plastic bag in the fridge.
When ready to bake, preheat oven to 350 degrees. Remove casserole from the fridge and sprinkle evenly with the topping mix.
Bake for 45 minutes for a softer, more bread pudding texture, or for 1-hour plus for a firmer, crisper texture.
Serve with butter and warm syrup.
You can also freeze the casserole unbaked - just put it in the fridge overnight to thaw, sprinkle with topping and bake.