Hot Cocoa Rice Krispie Treats

Bahan-bahan (15 porsi)

• 5 tablespoons unsalted butter
• One 16-ounce bag large marshmallows
• ½ teaspoon vanilla extract
• ½ cup finely chopped semisweet chocolate
• 6 cups Rice Krispies cereal
• 1 cup tiny dehydrated marshmallows ((or more, if you'd like))