📖 Instructions

1. **Choose Your Bread Wisely:** First things first, grab your loaf of bread. Challah or brioche work wonders here, but even a good quality white sandwich bread or French bread will do. The key? It needs to be slightly stale, like day-old bread. This helps it soak up all that yummy custard without turning into mush. If your bread is fresh, cut it into 1-inch cubes (about 8-10 cups total), and then lay them out on a baking sheet for an hour or two to dry out a bit, or even toast them lightly in a 250°F (120°C) oven for about 15 minutes. Once cubed, set aside.
2. **Grease and Arrange:** Take your 9x13 inch baking dish and give it a good spray with non-stick cooking spray, or smear it with about a tablespoon of soft butter. This helps prevent sticking and makes cleanup a breeze. Now, evenly spread those bread cubes into the prepared dish. Try to get them in a single layer, or as close as you can, without pressing them down too much.
3. **Whip Up the Custard:** In a large mixing bowl, crack the 6 large eggs. Whisk them vigorously until they're light and a little frothy, maybe 30 seconds to a minute. This aerates them and helps create a lovely, light custard. Now, pour in the 2 cups of whole milk and 1/2 cup of heavy cream. Add the 1/2 cup of granulated sugar, 2 tablespoons of packed light brown sugar, 2 teaspoons of pure vanilla extract, 1 teaspoon of ground cinnamon, and that tiny pinch of salt (don't skip the salt, it balances all the sweetness!). Whisk everything together *really* well until the sugars have dissolved and the mixture is smooth and evenly combined.
4. **Custard Bath Time:** Carefully pour the egg and milk mixture over the bread cubes in your baking dish. Make sure every single piece of bread gets drenched. You might need to gently press down on some of the bread cubes with a spoon or your clean hands to help them soak up the liquid. You want them completely submerged if possible.
5. **Blueberry Bonanza:** Evenly scatter the 2 cups of fresh or frozen blueberries over the top of the bread. If using frozen, there's no need to thaw them first! They'll bake up perfectly. Try not to stir them in too much, as you want them mostly on top for that beautiful burst of color.
6. **The Overnight Chill (Crucial Step!):** Cover the baking dish tightly with plastic wrap or aluminum foil. Pop it into the refrigerator and let it chill for at least 4 hours, but preferably overnight (8-12 hours). This extended soaking time is critical; it allows the bread to fully absorb the custard, giving you that wonderfully moist, custardy interior rather than a dry or soggy one.
7. **Morning Bake Prep:** The next morning, or whenever you’re ready to bake, pull the dish out of the fridge about 20-30 minutes before baking to let it come closer to room temperature. While it's sitting out, preheat your oven to 375°F (190°C).
8. **Bake Until Golden:** Once the oven is preheated, remove the plastic wrap from the baking dish. Place the French toast bake into the preheated oven. Bake for 45-55 minutes, or until the top is beautifully golden brown, puffed up, and the custard is set in the center. A good test is to insert a knife into the center; if it comes out clean (or mostly clean), it's done. If it seems to be browning too quickly, you can loosely tent it with foil.
9. **Cool and Serve:** Let the French toast bake cool for about 10-15 minutes before serving. This allows it to set a bit more and makes it easier to cut. Dust generously with powdered sugar, if you like, and drizzle with warm maple syrup. Slice into generous portions and serve immediately. It's truly best enjoyed warm!
10. **Optional Toppings:** Feel free to get creative! A dollop of whipped cream, a scoop of vanilla ice cream (yes, for breakfast!), or a sprinkle of chopped nuts can elevate this already delicious bake.