Cut up the bread slices into bite-sized bits.
Put the bread pieces, sugar, and cinnamon in a large bowl.
In another bowl, mix in all of the wet ingredients (milk, coffee creamer, eggs, melted butter, maple syrup, and vanilla).
Gently pour the liquid onto the bread pieces.
Fold over carefully until all of the bread has absorbed the liquid.
Use a large spoon and gently transfer the wet bread into a large resealable freezer bag.
If you are using the oats and cinnamon topping, put that in a medium-sized resealable bag and staple it to the large bag above the seal.
On the day of baking, move from the freezer to the fridge the night before or thaw for 30 minutes so you can pour it out of the bag into a 9x13 glass oven-friendly container.
Sprinkle the oats topping and bake at 400° for 30-40 minutes until the top is golden brown.
Pour maple syrup over the entire casserole or over individual portions when serving.