# Fresh Basil Pesto Pasta

Pesto pasta is pasta tossed with a fresh sauce of basil, pine nuts, garlic, Parmesan and olive oil. It is bright, herby and rich, and a jar of homemade pesto beats any store-bought version.

A quick blanch keeps the basil bright green, and a splash of pasta water turns the thick paste into a silky sauce.

- Total time: 27 min (prep 15 min, cook 12 min)
- Serves: 4
- Per serving (estimated): 640 kcal, 17 g protein
- Cuisine: Italian. Category: Main course. Diet: vegetarian.

## Ingredients

- 340 g fusilli or trofie
- 2 cups packed fresh basil leaves (about 60 g)
- 1/3 cup pine nuts, lightly toasted
- 2 cloves garlic
- 1/2 cup grated Parmesan, plus more to serve
- 1/2 cup extra-virgin olive oil
- 1 tbsp fresh lemon juice
- 1/2 tsp salt
- 1 cup cherry tomatoes, halved (optional)

## Method

1. Toast the pine nuts in a dry skillet over medium heat for 2 to 3 minutes, stirring, until golden and fragrant. Let them cool.
2. Bring a pot of water to a boil. Blanch the basil leaves for 10 seconds, then lift them into ice water. Squeeze dry and pat on a towel. This keeps the pesto bright green.
3. Add the basil, pine nuts, garlic, Parmesan and salt to a food processor. Pulse until finely chopped.
4. With the processor running, pour in the olive oil in a slow stream. Add the lemon juice and pulse once to combine. Taste and adjust salt.
5. Bring 4 liters (4 quarts) of water to a boil with 1 tbsp salt. Cook the pasta until al dente. Scoop out 1 cup of pasta water, then drain.
6. Return the hot pasta to the pot off the heat. Add about 2/3 of the pesto and 1/4 cup of pasta water, and toss until the sauce is creamy and coats the pasta.
7. Add more pesto or pasta water as needed. Fold in the cherry tomatoes if using, and serve with extra Parmesan.

## Why it works

- Toasting the pine nuts brings out their sweetness and gives the pesto a deeper, nuttier flavor.
- Blanching the basil for 10 seconds stops the enzymes that turn it brown and keeps the sauce bright green.
- Pulsing the ingredients first, then adding oil slowly, creates a smooth, blended sauce.
- A splash of lemon juice lifts the flavor and slows browning.
- Tossing the pasta off the heat with starchy water keeps the pesto from turning oily or dark.

## The science

- **Why pesto turns brown.** Cut basil contains an enzyme that reacts with oxygen and turns the leaves brown. A quick blanch deactivates the enzyme, and a little lemon juice slows what is left. A layer of oil on top also blocks air when you store pesto.
- **Heat dulls fresh herbs.** Basil gets its aroma from delicate volatile compounds that fade with heat. Tossing the pesto with pasta off the heat, using only a little pasta water to loosen it, protects that flavor and keeps the sauce fresh-tasting.

## Tips

- Reserve a cup of pasta water before draining because pesto is very thick.
- Pack the basil lightly when measuring, since a firmly packed cup holds much more.
- Cover leftover pesto with a thin layer of olive oil before storing.

## Mistakes to avoid

- Cooking the pesto in a hot pan, which turns it dark and dull, so toss it with the pasta off the heat.
- Skipping the pasta water, which leaves the sauce thick and clumpy, so thin it with a few spoonfuls.
- Using too much garlic, which can overwhelm the basil, so start with two cloves.

## Variations and swaps

- Swap pine nuts for walnuts or almonds to make it more affordable.
- Stir in a few spoonfuls of ricotta for a creamy pesto pasta.
- Add grilled chicken or shrimp and a handful of baby spinach.
- Swap basil for half basil and half baby spinach to stretch the pesto and keep it green.
- Swap Parmesan for Pecorino Romano for a sharper, saltier pesto.
- Swap pine nuts for sunflower seeds if you need a nut-free pesto.

## Storage

Refrigerate leftover pasta within 2 hours and eat within 3 days. Pesto alone keeps 5 days in the fridge under a layer of olive oil, or freezes for 3 months in an ice cube tray.

## FAQ

**How do I keep pesto from turning brown?**

Blanch the basil for 10 seconds, shock it in ice water and squeeze it dry before blending. Add a little lemon juice, and cover stored pesto with a thin layer of olive oil.

**Do I cook pesto before adding it to pasta?**

No, pesto is a raw sauce. Toss it with hot pasta off the heat, thinned with some pasta water, so the basil stays fresh and bright.

**Can I make pesto without pine nuts?**

Yes. Walnuts, almonds, cashews or sunflower seeds all work, and each gives a slightly different flavor. Toast them lightly first for the best taste.

**Can I freeze pesto?**

Yes. Freeze pesto in an ice cube tray, then move the cubes to a bag for up to 3 months. Thaw a cube or two in the fridge or stir it into hot pasta.

**Why is my pesto bitter?**

Bitterness can come from over-processing the basil, or from using a strong, grassy olive oil. Pulse briefly, use a mild extra-virgin olive oil, and add a pinch of salt or more cheese.

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Source: https://cookingscientist.com/recipes/pesto-pasta (Cooking Scientist). Learn the science of cooking in the Cooking Scientist app for iPhone and iPad: https://apps.apple.com/app/id6830326846