Arrange a rack in center of oven; preheat to 300°. Draw a 9" circle in the center of a piece of parchment, turn over, and place on a baking sheet.

In the large bowl of a stand mixer fitted with the whisk attachment, beat egg whites and salt on medium-high speed until foamy, about 1 minute. With the mixer running, slowly add sugar and beat until thick, glossy, and stiff peaks form, 8 to 12 minutes. Beat in cornstarch, vinegar, and vanilla until combined.

Spoon 8 (2") dollops of meringue onto parchment around the drawn circle, making sure each dollop touches to form a wreath shape. Using the back of spoon, form a shallow well in the center of each mound.

Place meringue in oven and immediately reduce oven temperature to 250°. Bake until set but still white, about 1 hour, 15 minutes. Turn off oven and let pavlova cool completely in oven with the door closed until it’s a pinkish beige color, and crisp and dry on the outside, at least 2 hours and up to overnight.

Meanwhile, in a small saucepan over medium heat, cook ½ c. sugar and ½ c. water, stirring frequently, until sugar dissolves and starts to simmer around the edges, about 4 minutes. Remove from heat, stir in cranberries, and let cool.

Stir in rosemary. Using a slotted spoon, transfer cranberries and rosemary to a wire rack set in a baking sheet to drain. Let dry until sticky but no longer wet, about 30 minutes.

Place remaining ¼ c. sugar in a shallow dish. Working in batches if needed, add cranberries and rosemary and toss to coat.

In the large bowl of stand mixer fitted with the whisk attachment, beat cream and sugar on medium speed until soft peaks form, 2 to 3 minutes. Gently fold in preserves.

Using a butter knife, loosen edges of pavlova. Carefully slide onto a platter. Spread whipped cream over. Top with raspberries, pomegranate seeds, and sugared cranberries and rosemary.