These French Toast Muffins combine the comforting flavors of classic French toast with the convenience of individual servings. Made with brioche bread soaked in a cinnamon-sweetened custard, then topped with a buttery cinnamon streusel, they are perfect for make-ahead breakfasts or brunches. Refrigerated overnight and baked until golden, these muffins are delightfully tender with a crisp, crumbly topping.