Begin by heating sunflower oil in a heavy-bottomed pot over medium-high heat until it reaches 350°F (175°C).

Slice the zucchini into thin rounds. Carefully add the zucchini in batches to the hot oil and fry for 5-7 minutes until golden and blistered. Remove using a slotted spoon and drain on paper towels.

Transfer the fried zucchini to the refrigerator to cool for at least 30 minutes.

Bring a large pot of salted water to a boil and add the spaghetti. Cook according to package instructions until al dente, usually 8-10 minutes. Reserve 1 cup of the starchy pasta cooking water before draining.

In a large frying pan, heat olive oil over medium heat. Add the chilled zucchini and stir in two ladles of reserved pasta water. Simmer for a few minutes.

Add the drained spaghetti to the frying pan and gently toss to combine. Stir in the grated Parmesan cheese and butter after removing from heat.

Serve immediately, garnished with extra Parmesan cheese and fresh basil leaves.