Meanwhile, place olive oil, garlic, and pepper flakes in a large cold pan and bring to a sizzle together, stirring occasionally so the garlic doesn’t burn. When the garlic becomes slightly golden and fragrant, add the tomatoes, along with some salt and pepper, and cook for about 1 minute. They should only be slightly softened, and release a little juice, but still hold their shape. Add the cooked drained spaghetti, along with a splash of the reserved salted cooking water to the pan. Add the lemon juice and toss together for 30 seconds, just to coat the spaghetti with the tomatoes. Turn off the heat and add the zucchini ribbons. Toss lightly and let the heat of the spaghetti slightly wilt the zucchini. Don’t let it soften too much or it can get mushy. Season with salt and pepper to taste. Top with feta and basil and serve.