Preheat your skillet over medium-low heat until it feels warm to the touch, about 150°C (300°F).
Mix the cinnamon and sugar in a shallow dish until evenly combined; set aside.
Spread a thin layer of melted butter on each slice of gluten-free bread, ensuring all sides are coated.
Dunk each bread slice into the cinnamon-sugar mixture, pressing gently to coat both sides thoroughly. Shake off excess.
Place the coated slices onto the warm skillet, hearing a gentle crackle as they make contact.
Cook the slices for about 2-3 minutes until the bottoms turn golden brown and crispy, then flip carefully with a spatula.
Cook the other side for another 2-3 minutes until similarly golden and fragrant, with caramelized cinnamon visible.
Transfer the toasted slices to a plate, allowing them to rest for a minute to set the caramelized cinnamon sticky coating.
Enjoy your warm, crispy, and sticky gluten-free cinnamon toast as a delightful breakfast or snack.