How to Make It
Preheat oven to 450º.
Place the egg whites and salt in a large bowl, and beat with a mixer at medium speed until foamy. Add the cream of tartar; beat for 1 minute. Gradually add the sugar, 1 tablespoon at a time, beating until well blended (about 8 minutes). Add vanilla extract. Increase mixer speed to high, and beat for 5 minutes or until soft peaks form. (Do not underbeat.) Coat the inside of a 10-inch springform pan with butter, and add meringue, spreading evenly. Break air pockets by cutting through meringue with a knife.
Place pan in 450° oven. Turn the oven off, and cool in closed oven for at least 24 hours.
Drain the raspberries, reserving 1/4 cup liquid. Place raspberries in a food processor, and process until smooth. Press raspberry mixture through a fine sieve into a bowl to measure 1 1/4 cups. Discard solids. Stir in the reserved raspberry liquid. Spoon cooled meringue into bowls. Drizzle with raspberry mixture, and top with whipped topping.
Note: Egg whites that have been beaten until soft peaks form maintain a glossy appearance. The texture of the whites is only lightly stiff.