- In a bowl, beat the egg whites and cream of tartar with an electric mixer until soft peaks form. Gradually add the sugar, beating constantly, until stiff peaks form, about 5 minutes.
- Add 1 1/2 cups of raspberries and beat for 1 minute.
- Divide the raspberry mousse among glasses or small bowls. Serve immediately or refrigerate for several hours.
- When ready to serve, top with the remaining raspberries.