What Is Pesto? Ingredients, History, and Uses on Pizza

Pesto is an Italian sauce originating from Genoa, made by grinding fresh basil, pine nuts, garlic, Parmesan cheese, and olive oil into a thick, bright green paste. The name comes from the Italian "pestare," meaning "to pound" or "to crush" — a reference to the traditional mortar-and-pestle preparation. Unlike cooked sauces, pesto is raw, which preserves the volatile aromatic compounds in basil that give the sauce its signature intensity. It is one of the simplest and most versatile sauces in Italian cooking.

Where Does Pesto Come From?

Pesto alla genovese — the original basil pesto — comes from Genoa, the capital of Liguria on Italy's northwest coast. The Ligurian climate produces a particular strain of basil (basilico genovese DOP) that is smaller-leafed, sweeter, and less peppery than the large-leafed basil common in American supermarkets. This basil is the foundation of authentic pesto.

The sauce has ancient roots. Roman moretum — a paste of herbs, cheese, garlic, and olive oil ground in a mortar — is a likely ancestor. But the modern pesto recipe was codified in the 19th century, and Genoa remains its spiritual home. The city takes pesto seriously: the Campionato Mondiale di Pesto Genovese (World Pesto Championship) is held every two years, and contestants must use a mortar and pestle.

What Are the Ingredients in Traditional Pesto?

Each ingredient in pesto alla genovese plays a specific role.

• Fresh basil: The dominant flavor. Provides the herbaceous, slightly sweet, anise-adjacent aroma. Must be fresh — dried basil produces a completely different (inferior) result. Use about 2 packed cups of leaves for a standard batch.
• Pine nuts (pignoli): Add creaminess and a subtle, buttery richness when ground. They also help emulsify the sauce. Lightly toasting them before grinding deepens the flavor. About 3 tablespoons per batch.
• Garlic: One to two cloves, raw. Provides the pungent kick that balances the sweetness of basil. Too much garlic overwhelms the basil — restraint is critical.
• Parmigiano-Reggiano: Adds salt, umami, and body. Some recipes include Pecorino Romano for a sharper edge. About half a cup of finely grated cheese.
• Extra-virgin olive oil: Binds everything together and adds fruity richness. Ligurian olive oil is mild and buttery — not the grassy, peppery Tuscan style. Use about half a cup, drizzled in gradually while grinding.

What Are Common Pesto Variations?

Pesto alla genovese is the classic, but the concept of ground herb-and-nut sauces extends across Italian cooking and beyond.

• Pesto rosso: Sun-dried tomato pesto. Replaces basil with sun-dried tomatoes and often substitutes almonds for pine nuts. Deeper, sweeter, and more concentrated than green pesto.
• Pesto alla siciliana (pesto trapanese): From Trapani, Sicily. Uses almonds, tomatoes, basil, and garlic. Brighter and more acidic than Genoese pesto.
• Pesto di rucola: Arugula pesto. Peppery and more assertive than basil pesto. Works well on pizza where you want a stronger green flavor.
• Walnut pesto (salsa di noci): From Liguria as well. Walnuts replace pine nuts and basil is reduced or omitted. Richer and more earthy.
• Kale pesto: A modern adaptation that swaps basil for lacinato kale. Heartier and slightly bitter, with added nutritional density.

How Does Pesto Work on Pizza?

Pesto on pizza replaces tomato sauce as the base layer, creating a fundamentally different flavor profile — herbal and nutty instead of acidic and sweet. The heat of the oven concentrates the basil oils and slightly toasts the pine nuts in the sauce, intensifying both flavors. The key is applying pesto sparingly: it is more concentrated than tomato sauce, and too much makes the pizza oily and one-note.

The best pesto pizzas pair the sauce with ingredients that complement its richness. Fresh mozzarella, roasted chicken, sun-dried tomatoes, roasted red peppers, and arugula all work well. Avoid heavy, salty toppings like pepperoni or sausage — they compete with the pesto instead of harmonizing.

Pesto is not just a sauce. It is a preservation method — a way to capture the peak of basil season in a form that delivers maximum flavor with no cooking required.

Is Pesto Vegetarian?

Traditional pesto contains Parmigiano-Reggiano, which is made with animal rennet — so technically, classic pesto is not vegetarian by strict definitions. However, pesto made with vegetarian Parmesan (using microbial rennet) or nutritional yeast is fully vegetarian and vegan-adaptable. At Forni, our cheeses use microbial rennet, so pesto-based pizzas work for vegetarians.

Pesto Pizza at Forni

Our kitchen uses pesto as an alternative base for build-your-own pizzas. The 800-degree stone oven transforms pesto in a way that a home oven cannot — the extreme heat concentrates the basil oils in seconds, deepening the flavor without burning the delicate sauce. Paired with our 48-hour fermented dough and halal-certified toppings, a pesto pizza at Forni is a departure from the traditional red pie that rewards anyone willing to try something different. Visit us at 5800 Seminary Rd in Falls Church.

Want to explore more pizza sauce options? Read our pizza sauce vs marinara guide →