Pulse the cranberries in a food processor until fine and no large pieces remain.

Transfer to a large mixing bowl and stir in the sugar.

Cover and refrigerate for at least 2 hours or up to overnight.

Drain any accumulated juices from the cranberries and reserve for another use.

Stir in the marshmallows, drained pineapple, pecans and orange zest, set aside.

Whip the heavy cream in a large chilled mixing bowl until the cream begins to thicken, about 1 minute.

Beat in powdered sugar and vanilla until soft peaks form, 3 to 5 minutes.

Fold the whipped cream into the cranberry mixture, one-third at a time, until fully incorporated.

Transfer to an 8 x 8 inch baking dish.

Refrigerate or freeze for about 2 hours.

Right before serving, garnish with the pomegranate seeds