Dissolve the cranberry jello in 2 cups of boiling water. Stir well until the jello granules are fully melted, which should take just a couple of minutes.

Mix in 1 cup of cold water along with the can of whole berry cranberry sauce. This adds rich flavor while cooling down the mixture slightly.

Incorporate the diced apples and chopped walnuts into the jello mixture. Gently fold them in to ensure even distribution without breaking the apples.

Pour the mixture into a serving dish, ensuring it's spread evenly. Cover with plastic wrap and refrigerate until set, typically about 4 hours or until firm.

Top with mini marshmallows just before serving. This adds a fun, fluffy texture that your guests will adore!