Classic Basil Pesto Pasta

From the garden

• 4 cups fresh basil leaves, packed, washed and dried well
• 2 cloves garlic
• ½ cup walnuts, lightly toasted — or traditional pine nuts

From the pantry

• ¾ cup finely grated parmesan — plus more for serving
• ½ cup olive oil
• 1 lb trofie, linguine, or spaghetti
• salt — to taste
• black pepper

1. Put a big pot of water on to boil and salt it well. Toast the walnuts in a dry skillet over medium heat, tossing, 3–4 minutes until fragrant; let them cool.
2. Blitz the garlic and walnuts in a food processor until finely chopped. Add the basil and a pinch of salt and pulse — short pulses, scraping down the sides — until finely chopped but still vividly green, not a purée. Overworking heats the basil and dulls it.
3. With the machine off between additions, pulse in the olive oil in two or three goes, then stir in the parmesan by hand for a properly rustic texture. Taste and season — it should be bold, salty, and almost too garlicky on its own.
4. Cook the pasta until al dente. Just before draining, scoop out a full cup of the starchy cooking water.
5. Off the heat — never over a flame, which cooks the basil brown — toss the pasta with the pesto and splashes of pasta water until a glossy green sauce clings to every strand. Serve immediately with more parmesan and black pepper.