Name: Peanut Butter Cups
Ingredients: 1 pound peanut butter; 10 pounds sugar; 1 teaspoon cream of tartar; 2 quarts water; 1 tablespoon burnt sugar color; vanilla (to taste)

Why it works: Butter and cream are a kitchen classic. They rank in the top 8% of all ingredient pairs, and cooks put them together in 41,516 recipes. Both carry delta-dodecalactone, which smells sweet, creamy. The science ↓

Peanut Butter Cups

Ingredients

Directions

Make the syrup

Heat the peanut butter in a double boiler.
Combine sugar, cream of tartar, and water in a kettle.
Set the kettle on fire and mix the contents.
When the mixture starts to boil, remove the paddle.
Wash the sides of the kettle with a wet brush.
Cover the kettle and allow it to steam for a few minutes.
Remove the cover, insert a thermometer, and cook until it reaches 335°F (170°C).
Add burnt sugar color and mix well.

Knead and shape

Pour the mixture onto a greased slab.
Turn the edges of the slab in.
Wearing gloves, knead the mixture until it is stiff enough to handle and shiny.
Flavor the mixture with vanilla while kneading.
Form the mixture into a flat square about 16 inches on each side.
Spread peanut butter on the square and roll it up, sealing both ends.
Pull the roll to about the size of your finger and cut with a butter‑cup cutter.

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.

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.

Butter + creamtop 8% of all pairs

Smell alikemoderate

Cooked together41,516 recipes

Shared aroma: delta-dodecalactone (sweet, creamy).
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).
Peanut + vanillatop 10% of all pairs

Smell alikestrong

Cooked together1,176 recipes

Shared aroma: guaiacol (smoky, sweet).
Butter + vanillatop 14% of all pairs

Smell alikemoderate

Cooked together20,050 recipes

Shared aroma: guaiacol (smoky, sweet).

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: Forms the bulk of the candy and sets into a firm, brittle structure as it cooks.
Peanut butter: Provides the nutty flavor and fat in the filling rolled into the candy.
Cream of tartar: Acidifies the syrup, helping prevent crystallization so the candy stays smooth.

The step that matters

Cooking to 335°F (170°C). Syrup cooked to this hard-crack range sets firm when cooled. Undercooked syrup stays soft and sticky, while overcooked syrup turns hard and brittle, so the thermometer reading matters.

Swap the peanut

How well each one fits the dish's main ingredients (butter, sugar, cream, vanilla):

Almondfits better
Chestnutfits better
Hazelnutfits better
Peanutthe original

Fit is the average pairing score against butter, sugar, cream, vanilla. Candidates are from the same food group and used in at least 100 recipes.

“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.

Vanilla Ice Cream108 recipes

Peanut Candy82 recipes

White Cake431 recipes

Pound Cake373 recipes

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Peanut Butter Cups