Basil is the backbone of this vibrant no-cook basil-walnut pesto sauce. Toss in some leftover roast chicken or pork with these zucchini noodles for a heartier meal.
Using a spiral vegetable slicer or peeler, cut zucchini (or summer squash) lengthwise into long, thin strands (stop when you reach the seeds). Place the strands in a colander and toss with 1/4 tsp. salt. Let drain for at least 15 minutes, then gently squeeze them to remove any excess moisture. Pile the strands on a cutting board and chop them once or twice to break them up.
Meanwhile bring a large pot of water to a boil. Cook spaghetti according to package directions. Reserve 1/2 cup of the cooking water, then drain.
Combine basil, walnuts, garlic, 5 Tbsp. oil, Parmesan, lemon juice, pepper, and the remaining 3/4 tsp. salt in a mini food processor. Process until smooth. Transfer to a large bowl.
Heat the remaining 1 Tbsp. oil in a large skillet over medium-high heat. Add the squash strands and cook, stirring, until warmed and slightly tender, about 3 minutes. Transfer to the bowl with the pesto. Add the spaghetti and toss to combine. If the mixture seems dry, add the reserved cooking water a little at a time. Garnish with additional basil, if desired.
Equipment: Spiral vegetable slicer, mini food processor
Tip: You can skip Step 1 and use 2 lbs. of premade zucchini noodles.