Arrange half the bread cubes in the prepared baking dish. Evenly distribute cream cheese cubes over the bread cube layer; sprinkle 1 1/2 cups sliced strawberries atop cream cheese layer. Layer the remaining bread cubes over strawberry layer.
Pour half-and-half into a blender; pulse for a few seconds. Blend eggs into half-and-half until fully incorporated. Add maple syrup and blend until smooth. Pour mixture evenly over bread mixture. Cover the baking dish with aluminum foil and refrigerate 8 hours or overnight.
Remove baking dish from refrigerator 45 minutes before baking.
Preheat oven to 350 degrees F (175 degrees C).
Bake the covered casserole in the preheated oven for 30 minutes. Remove aluminum foil and continue baking until French toast is puffed and golden brown, about 30 more minutes.
Stir sugar, water, and cornstarch together in a small saucepan. Cook, stirring occasionally, over medium heat until mixture has thickened, about 5 minutes. Mix in 1 cup sliced strawberries; cook and stir until strawberries have softened, about 10 minutes. Add butter; stir until melted. Serve hot over French toast.