Preheat oven to 350 degrees F.
Heat 1 cup sugar and water until sugar has dissolved and liquid measures 250 degrees F. Whip egg whites, cream of tartar, and salt until soft peaks form. With mixer running, add hot sugar liquid in a steady stream. Keep mixing until hard peaks form (one to two more minutes). Allow to cool.
Line a baking sheet with parchment paper. Using a spatula or spoon, form eight meringue mounds. With a smaller spoon, swirl melted chocolate into each pavlova. Bake for 30 minutes or until lightly browned, firm, but slightly spongy. Allow to cool.
While pavlovas are baking, heat cranberries, oranges, zest, and sugar until a fruit softens and a soft, sugary liquid forms. Remove from heat; allow to cool.
In a standing mixer, whip heavy cream and sugar until stiff peaks form.
Top each of the eight meringue pieces with a dollop of whipped cream. Top that with fruit mixture. Garnish with chocolate shavings and powdered sugar if desired.