Line your 9x13 inch baking pan with parchment paper, leaving some overhang on the sides.

Pour 4 cups of Special K cereal into a large bowl and set aside.

Place a medium saucepan over medium heat and add 3 tablespoons of butter, melting completely for about 1 minute without browning.

Add 4 cups of mini marshmallows to the melted butter and stir constantly for 2 to 3 minutes until smooth and creamy.

Remove the saucepan from heat and stir in 1 teaspoon of vanilla extract and 1/4 teaspoon of salt.

Pour the marshmallow mixture over the cereal and fold together with a spatula until evenly coated.

Transfer the coated cereal mixture into the prepared pan and press down firmly with a spatula or spoon handle.

Let the bars sit at room temperature for at least 30 minutes or refrigerate for 15 minutes until set.

Lift the set slab using the parchment overhang and cut into 24 bars with a sharp knife, wiping the blade between cuts.