Start by greasing a 9×13-inch baking dish generously with butter. This step is crucial—it not only keeps the casserole from sticking but also creates a lightly crisp and golden crust along the edges. If you prefer a dairy-free option, you can substitute with a neutral oil.

In a large bowl, whisk together the milk, cream, eggs, sugar, maple syrup, cinnamon, and nutmeg. Make sure the mixture is smooth and the spices are evenly distributed. This custard will soak into the bread and give the casserole its creamy, tender texture.

Add the bread cubes directly into the bowl of custard. Stir gently to ensure each piece is fully coated. Allow the bread to sit for a few minutes so it can absorb the liquid—this prevents dryness and ensures every bite is rich and moist.

Pour the soaked bread and any leftover custard into the greased baking dish. Use a spatula to spread the mixture evenly. Cover with foil or plastic wrap and refrigerate for at least 30 minutes. For deeper flavor, let it rest overnight in the fridge.

When ready to bake, preheat your oven to 350°F (175°C). If the dish was chilled overnight, allow it to come to room temperature while the oven preheats. Place the casserole in the center rack and bake uncovered for 45–48 minutes, or until the top is golden brown and set.

Once baked, let the casserole cool for 5 to 10 minutes. This helps it firm up, making it easier to slice. Serve warm with a drizzle of maple syrup, a dusting of powdered sugar, or fresh berries if desired.