Measure ¼ cup evaporated milk into a glass microwave safe mixing bowl and set aside for the caramel sauce.
In a second mixing bowl, add the remaining (1 ¼ cups) evaporated milk, eggs, sugar, 4 tablespoons melted butter, 2 teaspoons vanilla, cinnamon, salt, and nutmeg and mix well.
Pour over the bread cubes and toss to make sure bread is evenly coated with liquid. Slice 2 bananas and gently tuck the banana slices into the bread mixture. Set aside for 10 minutes to allow to bread to soak up most of the liquid.