Whisk together the eggs, milk, condensed milk, coffee, and salt in a large shallow dish.
Melt 2 tablespoons of butter on a large griddle over medium heat. Working in batches, dip the bread slices into the custard and turn to coat. Cook the bread slices for 3 to 4 minutes per side, until golden brown, adding more butter as needed.
Combine the powdered sugar, cocoa powder, and espresso powder in a small bowl. Dust the French toast with the powdered sugar mixture and serve with maple syrup for drizzling.