The day before you want to eat, slice the bread into thick-ish pieces, and arrange them in a shallow baking dish. Whisk together the eggs, sugar, vanilla and milk in a large bowl and pour evenly over the bread. Scatter over the blueberries and then cover with plastic wrap and place in the refrigerator overnight
The next morning, turn the oven on to 350F, no need to preheat. Remove the plastic from the French toast, and place in the oven. Bake for 35 minutes, or until golden brown and puffed up, with no liquid in the center (stab a knife in to check if you need to).
Serve the bake with a drizzle of maple syrup (and yogurt, if you want to be healthy) and some more fresh fruit on the side.
* If you don’t have brioche or challah, you can use a hearty white bread that is thick sliced (like “Texas toast” style)