1. Preheat oven to 200°. Trace 4 (3-inch) circles onto 2 sheets of parchment paper (8 circles total), leaving 1 inch between. Place paper onto baking sheets.
2. In a large bowl, beat egg whites with mixer on medium speed just until foamy. Increase speed to medium-high, add salt and cream of tartar, and beat until egg whites form soft peaks. Add 1/4 cup sugar, a tablespoon at a time, beating well after each addition. Beat just until stiff peaks form. Add vanilla. Fold in chocolate chips with a rubber spatula.
3. Starting at the center, spoon meringue onto the circles, using 1/2 cup per circle. Use a spoon to press in center of each meringue to shape it into a nest.
4. Place 1 baking sheet on the middle oven rack and 1 on the bottom. Bake for 1 hour or until set, switching sheets halfway through. Turn off heat; let cool in the oven 8 hours or overnight. Pavlovas will be crisp on the bottom.
5. Combine fruit mixture and remaining 2 teaspoons sugar in a bowl; let stand 5 minutes. Top each meringue with 1/2 tablespoon yogurt, then fruit. Serve immediately.