Beat eggs, vanilla, cinnamon, and sugar together in a bowl. Place bread into the egg mixture to soak.
Heat a lightly oiled skillet over medium heat and brown the slices of bread on both sides. Heat a smaller lightly oiled skillet over medium-low heat and pour the remaining egg mixture into the skillet. Allow the eggs to set in the skillet for 1 to 2 minutes, then continue to cook and stir eggs until scrambled.
Place 1 slice of toast onto a plate and top with the eggs. Layer the slices of banana over the eggs, then place the second slice of toast on top to make a sandwich.