Preheat your oven to 350°F (175°C) and prepare a tube pan.

Add room temperature egg whites to a mixing bowl and beat on medium speed until frothy, about 1-2 minutes.

Gradually add granulated sugar while beating, then increase speed to high until soft peaks form, about 3-4 minutes.

Sift cake flour over whipped egg whites and gently fold in using a spatula.

Carefully fold in raspberries, ensuring even distribution.

Pour batter into prepared tube pan, smoothing the top, and bake for 30-35 minutes until top is lightly golden.

Invert the pan immediately on a bottle or cooling rack to cool for at least an hour.

Once cooled, loosen edges with a knife and invert onto a serving plate; slice and serve.