Grease a 8x8'' baking pan with non-stick cooking spray or butter.
Cut the marshmallows with scissors into 4ths (dip the scissors in water after each cut to keep the marshamllows from sticking). Add cut marshmallow to the pan.
In a saucepan over low heat (or a double boiler) add chocolate and butter. Stir constantly until melted and smooth. Remove from heat and add the vanilla extract and walnuts, if using.
Slowly spoon melted chocolate over marshmallows, gently nudging the marshmallows with the spoon to allow the chocolate to seep into all of the cracks.
Refrigerate until set. Store leftovers in the refrigerator.
Video
Notes
Butter: using unsalted butter, add 1/8 tsp salt to the saucepan.Make Ahead Instructions: This Rocky Road candy recipe is a great make-ahead treat! Store it in an airtight container in the refrigerator for a couple weeks.Freezing Instructions: Store in an airtight freezer-safe container in the fridge for up to two months. Let thaw overnight in the refrigerator.