Basil Pesto Pasta with Blistered Tomatoes

Ingredients

• 400 g spaghetti or linguine
• 80 g fresh basil leaves, packed (about 3 large bunches)
• 40 g cashews or pine nuts, lightly toasted
• 2 garlic cloves, peeled
• 50 g Parmesan, finely grated, plus extra to serve
• 120 ml extra virgin olive oil
• 1 tsp lemon juice
• 250 g cherry tomatoes, halved
• 1 tbsp olive oil, for the tomatoes
• 1 tbsp salt, for the pasta water
• salt and freshly ground black pepper, to taste

Instructions

1. Bring 4 litres of water to a rolling boil in a large pot. While it heats, toast the cashews in a dry frying pan over medium heat for 3 to 4 minutes, shaking often, until pale golden. Tip them onto a plate to cool.
2. Pick the basil leaves from the stems and pat them dry. Put the basil, cooled nuts, garlic and Parmesan in a food processor and pulse until coarsely chopped.
3. With the machine running, pour in the olive oil in a steady stream. Add the lemon juice, a pinch of salt and some pepper, then blend until the pesto is thick and spoonable but still slightly textured. Taste and adjust the seasoning.
4. Add 1 tablespoon of salt to the boiling water, then the spaghetti. Cook for 1 minute less than the packet time, until just firm to the bite (al dente). Stir in the first minute so it does not stick.
5. While the pasta cooks, heat 1 tablespoon of olive oil in a large frying pan over high heat. Add the tomatoes cut side down and cook for 3 to 4 minutes, until the skins blister and the edges soften. Season lightly and turn off the heat.
6. Scoop out a mug (about 250 ml) of pasta water, then drain the spaghetti.
7. Return the pasta to the warm pot, off the heat. Add the pesto and 4 tablespoons of pasta water, and toss until every strand is glossy and coated. Add more water a spoonful at a time if it looks tight.
8. Fold in the blistered tomatoes and their juices. Serve straight away with extra Parmesan and black pepper.

Tips

• Never cook the pesto in the pan. Direct heat turns fresh basil dark and dulls the flavour, so toss it with the pasta off the heat.
• Pasta water is the secret to a silky sauce. The starch helps the oil cling to the noodles instead of pooling at the bottom.
• To keep the pesto bright green, blanch the basil in boiling water for 5 seconds, then chill it in iced water and dry it well before blending.
• Pat the basil completely dry, as wet leaves make the pesto watery.