Preheat oven to 300˚F.
For meringue: Place egg whites into a clean stand mixer bowl and whisk on medium speed until light and frothy. (If using cream of tarter and vanilla extract, add at this time)
With the motor running, gradually add sugar until mixture is thick, fluffy, glossy, and medium-stiff peaks form.
Scoop and shape mixture onto a parchment lined baking sheet and place into the oven.
Once pavlova is in the oven, reduce temperature to 250˚F and bake for about 1 hour. Turn oven off and allow pavlova to sit and cool completely, 1 to 2 hours.
For macerated berries: Place all ingredients into a bowl and fold together, lightly mashing berries together. Allow mixture to sit for at least an hour before using.
To assemble: Top pavlova with whipped cream (if using), followed by the macerated berries and serve.