Preheat the oven to 350°. Spray a large rimmed baking sheet (about 11 by 17 inches) with cooking spray; line it with parchment paper and spray paper. In a large bowl, using an electric mixer on medium, beat the egg whites, cream of tartar, and sea salt until foamy. Gradually beat in the sugar. Increase the speed to high and beat until stiff, glossy peaks form, about 4 minutes. Beat in 1 tsp. vanilla. Sift the cornstarch over the meringue; beat until blended. Using a spatula, fold in the raspberries and chocolate chips.