In a small bowl, mix the sugar, cinnamon, and salt; set aside.

Heat a large skillet over medium heat and add the butter.

Once the butter has fully melted, stir in the vanilla extract if using.

Add the Cheerios to the skillet and stir constantly for 3–5 minutes, until the cereal is well coated and lightly toasted.

Remove the skillet from heat.

Sprinkle the cinnamon-sugar mixture over the hot buttered Cheerios.

Stir or toss gently until every piece is evenly coated.

Spread the coated cereal on a plate or tray and let it cool completely before serving. The coating will crisp up as it cools.