Preheat oven to 425 degrees F. On a rimmed baking sheet, add the cauliflower florets, sliced onion, chopped garlic, olive oil, kosher salt, black pepper, and crushed red pepper flakes, if using. Toss together to coat everything well, spread out evenly, and roast for about 20 minutes, or until veggies start to brown and soften.

Remove the baking sheet from the oven and toss veggies to flip around and redistribute, spread out evenly on the pan. Sprinkle the top with the Panko breadcrumbs and place back into the oven, roasting for another 10 minutes or so, or until breadcrumbs are golden and veggies have browned and softened.

While cauliflower is roasting, cook the dry pasta until al dente according to package directions in heavily salted water.

Use a slotted spoon or tongs to transfer the cooked pasta directly into a large mixing bowl along with olive oil, capers, lemon juice, and chopped fresh parsley. If it all seems a bit dry, you can add a couple of tablespoons of the pasta cooking water.

Once cauliflower is done roasting, remove from the oven and toss with the pasta mixture. Taste and adjust seasoning if necessary. Serve garnished with more parsley and red pepper flakes, a drizzle of olive oil, and fresh cracked black pepper, if desired.