Grease a 12-cup muffin tin with butter or non-stick spray and preheat your oven to 350°F (175°C).

In a large mixing bowl, whisk together 4 eggs, 1 cup of whole milk, 1/2 cup of granulated sugar, 2 teaspoons of cinnamon, and a pinch of nutmeg until well combined.

Cut brioche into 1-inch cubes and gently fold them into the custard mixture, letting the bread soak for about 15 minutes.

Divide the soaked brioche and custard mixture into the prepared muffin cups, filling each cup just to the rim.

Melt 2 tablespoons of butter and brush it over the tops of each muffin, then sprinkle the cinnamon-sugar mixture on top.

Bake the muffins in the preheated oven for 20-22 minutes, until golden brown and a toothpick inserted comes out clean.

Remove the muffins from the oven and let them cool in the pan for about 5 minutes before transferring to a wire rack to cool completely.