Preheat your oven to 350°F (175°C) and prepare an ungreased 9-inch tube pan.

Sift the cake flour 4-5 times, mix in 3/4 cup of sugar and rainbow sprinkles, then set aside.

In a stand mixer, beat egg whites, cream of tartar, vanilla extract, and salt until frothy, then gradually add remaining sugar until stiff peaks form.

Gently fold the flour mixture into the whipped egg whites in three additions.

Pour the batter into the tube pan and bake for 45-50 minutes until golden brown.

Immediately invert the pan onto a wire rack to cool completely while upside down.

Whisk egg whites and sugar for frosting over simmering water until warm, then whip until light and fluffy.

Once cooled, frost the cake with marshmallow frosting and optionally torch the frosting for a golden hue.