Place two oven racks in the middle of the oven. Preheat the oven to 375 degrees F. Spray 2 baking sheets with nonstick spray (or line with parchment paper).
Place the tortillas on a cutting board. Brush generously with melted butter.
Place the sugar and cinnamon into a bowl and stir to combine. Sprinkle the buttered tortillas with the cinnamon-sugar mixture.
Place 2 tortillas on each baking sheet. Use a pizza cutter to cut them into chip-sized shapes. (Alternately, you can do this on a cutting board and transfer the pieces to the baking sheet, but you might lose a little of the cinnamon sugar as you do so). Spread the pieces apart a little bit on the baking sheet.
Bake 8 to 12 minutes, or until crispy and lightly browned,. The chips may begin to curl up on the edges. Rotate baking sheets during baking.
Notes
You might have leftover butter or sugar (these are generous amounts given in the recipe), but that just means you can make some more (or use a little less).
These are great to serve with a big mug of hot chocolate.