Place the egg whites in a large mixing bowl; let stand at room temperature for 30 minutes.
Meanwhile, line a 15x10-inch baking pan with waxed paper; lightly coat paper with cooking spray and set aside. Preheat oven to 350 degrees F.
Add vanilla and cream of tartar to egg whites; beat on medium speed until soft peaks form. Gradually beat in sugar, 2 tablespoons at a time, on high until stiff glossy peaks form and sugar is dissolved. Fold in flour, ¼ cup at a time.
Carefully spread batter into prepared pan. Bake for 15-20 minutes or until cake springs back when lightly touched. Cool for 5 minutes.
Dust a clean kitchen towel with 1 tablespoon powdered sugar. Turn the cake out onto the kitchen towel. Gently peel off waxed paper. Roll up cake in the towel jelly-roll style, starting with a short side. Cool completely on a wire rack.
Meanwhile, in a medium bowl, beat the cream on medium speed until it begins to thicken. Add powdered sugar and vanilla; increase the speed to medium-high and beat until soft peaks form. Gently fold in the strawberries. Store in the refrigerator until ready to use.
Unroll cooled cake; spread filling to within ½-inch of edges (you will have some filling leftover). Roll up again. Place seam side down on a serving plate; sprinkle with additional powdered sugar, if desired. Serve with any leftover strawberries and cream filling. Store leftovers, covered with plastic wrap, in the refrigerator.