Grease a loaf pan with butter or baking spray. Line the pan with parchment paper, leaving an overhang on each side.

Then, melt the butter over medium-low heat. Let it gently simmer, swirling the pan often, until the butter smells nutty and there are small brown bits on the bottom of the pan, about 5-7 minutes.

Add the 180 grams (3 ½ cups) of mini marshmallows to the brown butter. Stir the marshmallows constantly, just until they're melted and well-combined with the butter. Remove the pan from the heat and stir in the salt and vanilla extract. Add the Cinnamon Toast Crunch and remaining 20 grams (½ cup) of mini marshmallows. Stir until everything is well-combined and the marshmallows are slightly melted.

Using a greased rubber spatula, gently press the mixture evenly into the prepared loaf pan. Then, let the bars set at room temperature or in the fridge for about 30-60 minutes. Use the sides of the parchment paper to remove the treats from the pan. Slice into 6 bars and enjoy!