Heat your oven to 275°F (140°C) for 15 minutes.

To make the pavlova, place the egg whites in the bowl of an electric mixer. Whip the egg whites until they are cloudlike, fluffy yet firm, about 3-4 minutes. Overwhipped egg whites will have a rough, jagged texture so watch the egg whites closely as they are whipping.

While the egg whites are whipping, in a separate bowl, mix together the white sugar and brown sugar. Set aside. In a separate small bowl, mix together the cornstarch and vinegar. Set aside.

Once the egg whites appear fluffy and firm, add the sugar mixture one spoonful at a time, allowing to incorporate before adding the next spoonful, about 5 seconds. Once all of the sugar is incorporated, add the vinegar/cornstarch mixture.  Whip for 5-10 seconds more, blending well. Turn off the mixer. 

Cut a square of parchment paper and trace an 8″ circle (20-21 cm) onto the paper (I find this easiest to do by tracing around a clean mixing bowl) Trace 2 circles if you are making a double pavlova. Spoon the pavlova mixture onto the parchment, following the pencil circle as your guide. Leave a hollow portion in the middle of the pavlova. 

Bake in the preheated oven for 1 hour. After 1 hour, turn off the oven, and allow the pavlovas stay in the oven as it cools down, about 2-3 hours.

After the pavlova is completely cool, it is ready for filling and serving.