Name: Boiled Frosting
Ingredients: 1 cup sugar; ½ teaspoon cream of tartar; ½ cup boiling water; 1 egg white; 1 teaspoon vanilla or 1 tablespoon lemon juice

Why it works: Sugar and vanilla are a kitchen classic. They rank in the top 8% of all ingredient pairs, and cooks put them together in 35,032 recipes. Both carry beta-damascenone, which smells apple, rose. The science ↓

Boiled Frosting

Ingredients

Directions

Make the syrup

Combine sugar, cream of tartar, and boiling water in a saucepan; stir over low heat until sugar dissolves.
Boil gently without stirring until a soft ball forms in cold water (238°F).
Gradually cool the syrup.

Finish and serve

Slowly add the cooled syrup to the stiffly beaten egg white while continuing to beat until thickened.
Add flavoring.
Pour the frosting over the cake.

Recipe from a historical cookbook (Internet Archive).

Transcribed from a scanned cookbook and modernised for today's kitchens. Where the book gave no heat or time, or said "a moderate oven", the temperatures and times here may be modern equivalents rather than the book's own figures.

Photo for illustrative purposes only · Contact us to use it

Explore the science

The flavor team

The pairs that carry this dish. Each one is judged two ways: how much their aromas overlap, and how often cooks already put them together.

Sugar + vanillatop 8% of all pairs

Smell alikelow

Cooked together35,032 recipes

Shared aroma: beta-damascenone (apple, rose).
Sugar + creamtop 9% of all pairs

Smell alikemoderate

Cooked together43,450 recipes

Shared aroma: 2,3-butanedione (butter, sweet).
Cream + vanillatop 15% of all pairs

Smell alikelow

Cooked together12,301 recipes

Shared aroma: 2-nonanone (fruity, floral).
Sugar + eggtop 21% of all pairs

Smell alikemoderate

Cooked together122,807 recipes

Shared aroma: 2-nonenal (fatty, green).
Egg + vanillatop 23% of all pairs

Smell alikelow

Cooked together27,347 recipes

Shared aroma: 1-octen-3-ol (mushroom, earthy).

Sugar and vanilla barely smell alike, yet cooks put them together in 35,032 recipes: they work on texture and structure more than aroma.

Ranks compare each pair with 20,000 random ingredient pairs on CompKitchen. How we score pairs

What each ingredient does

Sugar: Provides sweetness and, once cooked into syrup, the body of the frosting.
Egg white: Whipped to a foam that traps air and gives the frosting its light, fluffy structure.
Cream of tartar: Acidifies the syrup, helping prevent crystallization so the frosting stays smooth.

The step that matters

Boil without stirring until a soft ball forms. Stirring during boiling can trigger sugar crystals that make the frosting grainy. The syrup must reach the soft-ball stage, about 238°F, so it has enough concentration to set into a stable foam when beaten into the egg white.

“What each ingredient does” and “The step that matters” were written by Claude from this recipe’s own method and reviewed in samples by CompKitchen.