Coat a baking pan with cooking spray or vegan butter.
Slice bread loaf into 16 pieces, and arrange on baking pan. Layer them like tiles on a roof.
In a blender or food processor add 1 banana, 1/2 cup cashews, 3 cups oat milk, 1 tsp cinnamon, 1/4 tsp nutmeg, 2 tbsp brown sugar, 2 tbsp flax meal, 2 tbsp aquafaba, and 1 tsp vanilla. Blend or process until smooth and creamy.
Pour mixture over bread. Try to make sure all bread gets coated. Let it rest for 15 minutes.
Meanwhile make the topping. In a bowl add 1 cup chopped walnuts, 2 tbsp vegan butter, 1/2 cup brown sugar, 1/2 tsp cinnamon, and 1/4 tsp nutmeg. Mix well with a fork.
Heat oven to 350 degrees.
After bread mixture has rested for 15 minutes, top the bread with the walnut topping. Distribute evenly.
Bake at 350 degrees for 40 minutes. Top french toast with syrup if you like (it's plenty good without it) and enjoy!