Spiced Pavlova with Roasted Pears and Grapes

Name: Spiced Pavlova with Roasted Pears and Grapes
Ingredients: 1 2/3 cups plus 2 tablespoons superfine sugar, divided; 2 tablespoons cornstarch; 3/4 teaspoon ground cardamom; 8 large egg whites, at room temperature; 2 teaspoons white vinegar; 3/4 teaspoon table salt; 1/4 teaspoon cream of tartar; 3 cups seedless red grapes; 1 teaspoon olive oil; 2 rosemary sprigs; 2 (8-ounce) firm red-skinned pears (such as Starkrimson), cored and cut into 12 wedges each; 1 1/2 cups heavy cream; 1/2 cup crème fraîche; 1/2 cup pomegranate arils; Fresh rosemary leaves, for garnish (optional)