Heat oven to 425° F. Brush both sides of the tortillas with the butter and sprinkle with 1 tablespoon of the sugar.
Bake the tortillas on 2 rimmed baking sheets, switching the sheets halfway through, until golden, 5 to 7 minutes per side.
In a medium bowl, toss the bananas with the lemon juice. Dividing evenly, top the tortillas with the bananas and sprinkle with the remaining 4 tablespoons of sugar.
Bake the tortillas, switching the sheets halfway through, until golden, 11 to 13 minutes. Drizzle with the caramel sauce.