Preheat oven to 350 degrees. Spray 8 (8-ounce) ramekins with cooking spray.
Combine the berries with ½ cup powdered sugar, 1 tablespoon cornstarch, the lemon zest, and lemon juice. Divide among the ramekins.
Beat the egg whites on high speed with the salt and cream of tartar until foamy. Gradually beat in 1/4 cup of sugar, about 1 tablespoon at a time. Beat until stiff peaks form.
Beat the egg yolks with ¼ cup sugar on high speed for 5 minutes or until very light in color and very thick. Beat in the remaining 2 tablespoons of cornstarch and the vanilla.
Fold the egg yolk mixture into the egg white mixture about 1/3 at a time. Mound on top of the berries, coming all the way to the edges of the ramekins.
Place the ramekins on a baking dish and bake for 30 minutes or until the topping is set and golden brown.
Dust with a little powdered sugar and serve warm with a little melted ice cream drizzled on if desired.