Preheat the oven to 400°F (200°C).
Prepare your vegetables. Halve any tomatoes that are larger than bite-size, chop broccoli florets into bite-sized pieces, no larger than 1 inch (25 mm), cut zucchini in half lengthwise then into 1/2 inch (12 mm) thick half-moons, and peel, smash, and roughly chop the garlic.
In a large baking dish or roasting pan, combine the vegetables and halloumi. Drizzle with olive oil, and sprinkle with salt and red pepper flakes, if using. Toss to combine, then spread in an even layer.
Roast vegetables and cheese, tossing once, until the vegetables and cheese begin to brown, 30 to 35 minutes.
While the vegetables are roasting, bring a large pot of heavily salted water to a boil. Cook pasta according to package directions, then drain, reserving 1/2 cup of pasta water.
Pour drained pasta into the baking dish, slowly add up to a 1/2 cup of the cooking water, tossing vegetables until everything is glossy.
Stir in lemon zest and juice, serve topped with chopped herbs and a drizzle of olive oil.