Preheat the oven and prepare a baking sheet lined with parchment paper.

In a clean bowl, whip the egg whites until soft peaks form, then gradually add the caster sugar until stiff peaks form.

Gently fold in the cornstarch, white vinegar, and vanilla extract.

Pipe the meringue onto the prepared baking sheet in a wreath shape.

Bake in the oven at a low temperature until dry and crisp, then allow to cool.

In a separate bowl, whip the heavy cream until soft peaks form, then fold in the mascarpone cheese, powdered sugar, and vanilla extract.

Add the green food coloring to the cream mixture until the desired color is achieved.

Assemble the wreath by spreading the green cream mixture on top of the cooled meringue.

Decorate with strawberries, raspberries, sugared cranberries, pomegranate, and rosemary sprigs.

Dust with powdered sugar before serving.