Set an iron skillet or a frying pan over medium heat. Grease with butter. Place tortilla on skillet.
Working on only half the tortilla (you'll be folding it over)...
Spread a light layer of pizza sauce over each tortilla. Divide up the toppings evenly over each flour tortilla. Don't overstuff.
Once cheese begins to melt, using a spatula, fold one side of the tortilla over the other. Cook just until lightly browned.
Serve while warm with additional pizza sauce, if desired.