1. Grease a 9-inch-by-5-inch loaf pan with ½ tablespoon of the butter and set aside.
2. In a small saucepan set over medium heat, add the Chartreuse. Bring to a simmer and cook over low heat until reduced by three-quarters, about 10 minutes.
3. Add the remaining 2 tablespoons of the butter and salt and stir until completely melted, about 2 minutes. Add the marshmallows and stir until completely melted, 3 to 4 minutes.
4. Turn off the heat and mix in the crisped-rice cereal, stirring just to combine. Stir in the chocolate chips and scrape the mixture into the prepared pan; using a rubber spatula, press it into an even layer. Set aside (or refrigerate) to set. Slice and serve.
Recipe adapted from Andrew Cross, Canon, Seattle, WA