Preheat your oven to 350°F (175°C). This ensures that your muffins will bake evenly and rise beautifully.
Grease your muffin tin with butter or line it with paper liners to make removing the muffins easier once they are baked.
Take your loaf of French bread and cut it into small cubes, about 1 inch in size. The older the bread, the better, as it will soak up the egg mixture without becoming mushy.
In a large mixing bowl, whisk together the eggs, milk, maple syrup, granulated sugar, cinnamon, and vanilla extract until well combined.
Gently fold the cubed bread into the egg mixture, ensuring that each piece is coated. Allow the mixture to sit for about 10 minutes, giving the bread time to soak up the flavors.
In a separate bowl, mix together the brown sugar, flour, cinnamon, and salt. Drizzle the melted butter over the mixture and use a fork to combine until crumbly.
Scoop the bread mixture into the prepared muffin tin, filling each cup about 3/4 full. Sprinkle the cinnamon streusel generously on top of each muffin.
Place the muffin tin in the preheated oven and bake for 20-25 minutes, or until the muffins are golden brown and a toothpick inserted into the center comes out clean.
Once baked, remove the muffins from the oven and let them cool in the tin for about 5 minutes. Then transfer them to a cooling rack. Before serving, dust with powdered sugar for an extra touch of sweetness.