1 brioche loaf, cut into 1-inch pieces
2 tbsp. fresh orange zest
3 tbsp. granulated sugar
9 large eggs
2 cups half and half
2 tsp. cinnamon
1 tbsp. vanilla extract
1 tsp. fine salt
1 tbsp. unsalted butter, plus more for the baking dish
1 cup maple syrup
2 tbsp. freshly squeezed orange juice
3 medium oranges, peeled and cut into segments
Generously coat 9 x 13-inch baking dish with butter. Add the bread cubes to the dish and set aside. Combine the orange zest and sugar in a small bowl. Use your fingers to rub the zest into the sugar until it’s well-combined and fragrant; set aside. Beat the eggs in a large bowl, then whisk in the orange sugar, half-and-half, cinnamon, vanilla, and salt. Evenly pour the custard over the bread. Use a spoon to push the bread down and stir so all the cubes are soaked through. Cover the dish with plastic wrap and refrigerate overnight.
Preheat oven to 350°. Bake uncovered until the casserole is set, puffed, and the top is golden-brown, 40 to 45 minutes. Meanwhile, prepare the syrup. Combine the maple syrup, orange juice, and orange segments in a medium saucepan. Cook over medium-high heat, stirring occasionally, until the syrup is slightly thickened, about 10 minutes. Stir in the remaining 1 tablespoon butter and remove from the heat. Serve in a small bowl alongside French toast.