Name: Welsh Rarebit
Ingredients: ½ pound grated cheese (ordinary Canadian); 2 tablespoons butter; 2 tablespoons milk; ⅓ cup ale or consommé; 1 tablespoon prepared mustard; ¼ teaspoon salt

Why it works: Butter and milk are a kitchen classic. They rank in the top 7% of all ingredient pairs, and cooks put them together in 81,283 recipes. Both carry (z)-4-heptenal, which smells biscuit, cream. The science ↓

Welsh Rarebit

Ingredients

Directions

Make the sauce

Melt the butter in a saucepan over medium heat.
Add the grated cheese and stir until melted.
Gradually mix in the ale, milk, or consommé, stirring constantly.
Add the mustard and salt, and continue stirring until smooth.

Serve

Pour the mixture over slices of hot buttered toast cut into diamond shapes.

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 + milktop 7% of all pairs

Smell alikemoderate

Cooked together81,283 recipes

Shared aroma: (z)-4-heptenal (biscuit, cream).
Cheese + buttertop 8% of all pairs

Smell alikemoderate

Cooked together7,962 recipes

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

Smell alikemoderate

Cooked together4,426 recipes

Shared aroma: delta-dodecalactone (sweet, creamy).
Cheese + mustardtop 11% of all pairs

Smell alikemoderate

Cooked together1,805 recipes

Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).
Butter + mustardtop 22% of all pairs

Smell alikemoderate

Cooked together8,003 recipes

Shared aroma: guaiacol (smoky, sweet).

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

What each ingredient does

Grated cheese: Melts into the sauce to provide the main body, richness and savoury flavour.
Butter: Adds fat and richness, helping the cheese melt smoothly without clumping.
Ale or consommé: Thins the cheese into a pourable sauce while adding liquid and flavour.
Milk: Adds moisture and mildness, helping keep the cheese sauce smooth and creamy.
Prepared mustard: Adds sharpness that balances the richness of the cheese.

The step that matters

Gradually mix in the ale, milk, or consommé, stirring constantly. Cheese proteins tighten and turn grainy or stringy when overheated or when liquid is added too fast. Adding the liquid slowly while stirring lets the emulsion form evenly, keeping the sauce smooth.