Preheat your oven to 350°F (175°C).

Melt butter in a large skillet over medium heat. Add bread cubes in batches and toast, stirring frequently until golden brown and crisp around the edges. Transfer toasted bread to a 9x13 inch baking dish.

In a saucepan, combine piloncillo (or brown sugar), cinnamon sticks, and water. Bring to a simmer, stirring until sugar dissolves. Simmer for 5-7 minutes until slightly thickened. Discard the cinnamon sticks.

In a bowl, whisk together evaporated milk, sweetened condensed milk, whole milk, and vanilla extract. Pour the warm syrup into the milk mixture while whisking constantly.

Scatter raisins and chopped nuts over the toasted bread. Pour the milk mixture over the bread, ensuring all pieces are submerged.

Sprinkle shredded cheese on top.

Place the baking dish in a roasting pan and add hot water to the roasting pan until halfway up the sides of the baking dish.

Bake for 50-60 minutes until golden brown and bubbly.

Let rest for 20 minutes before serving warm.