Heat broiler, with rack 4 inches from heat. Place tortillas on a baking sheet. In a small bowl, combine sugar and cinnamon. Dividing evenly, spread butter on one side of each tortilla; sprinkle with cinnamon sugar.
Broil until sugar is golden brown and has melted, 1 to 2 minutes. (Tortillas will puff under broiler and become flat again once taken out.) Cut each tortilla into wedges.