Spread each slice of Texas toast with about 2 tablespoons of chocolate peanut butter.
Arrange banana slices in an even layer on two of the slices, then top with the remaining slices so the peanut butter faces the bananas to form two sandwiches; set aside.
In a medium bowl, whisk together the eggs, milk, granulated sugar, and cinnamon until combined.
Heat the butter in a large skillet over medium-high heat until melted and foamy.
Quickly dip each sandwich into the egg mixture, coating both sides, allowing excess to drip off, then place in the hot skillet.
Cook about 3 to 4 minutes per side, or until each side is lightly golden brown and cooked through.
Slice the sandwiches in half and serve immediately while warm.