Preheat the oven to 180°C (350°F). Using a plate, bowl or cake pan to draw a circle between 7 and 8 inches (18-20cm) on a sheet of parchment paper. Place the paper drawn side down on a baking sheet and set aside.
Add the egg whites, cream of tartar and vanilla to the bowl of a clean stand mixer fitted with a whisk attachment and mix on medium-low. You can also use an electric hand mixer but if will require some patience.
Once the egg whites are frothy you can begin sprinkling in the sugar a tablespoon at a time.TIt is very important not to dump the sugar in but to add it very slowly. This way you will get a thick, glossy meringue with a marshmallowy texture.
Sprinkle the cornstarch onto the meringue and fold in using a spatula.
Mix on high speed until glossy stiff peaks form, about 2 more minutes. The peaks should be stiff enough that you can hold the whisk upright and the peaks won’t move.
Transfer the meringue to your prepared baking sheet .You can make decorative peaks with the back of a large spoon if desired. Make sure the edges are relatively tall and there is a nice dip in the center.
Place pavlova in the oven. As soon as you close the oven door, reduce heat to 90°C (200°F). Bake until the pavlova is firm and dry, about 90 minutes total. Turn the oven off and let the pavlova cool inside the oven
In the meantime prepare the chocolate whipping cream and the cherry sauce.