Heat water in a large pot to cook the pasta, and follow the directions on the package to cook to al dente. Scoop out ¼ cup of pasta water, and set aside. Drain.
Heat the olive oil in a large sauté pan over medium heat. Add the scallion and poblano and sautè, stirring occasionally, until softened and fragrent, about 2 minutes. Add the garlic and cook another 30 seconds. Add the romanesco florets and cook another 2 minutes. Add the apples and sautè until the apples are slightly soft, about 2 minutes.
Add the sauce and cooked pasta along with a couple tablespoons of the cooking water, and toss until everything is heated through, stirring occasionally, about 2 minutes. Top with the parsley, cheese, and breadcrumbs. Finish with a little salt and a few grinds of pepper. If you want a little more heat, sprinkle with a dried red pepper flakes.
Finish with a drizzle of olive oil and serve warm.
In a medium saucepan, cover the cauliflower and shallot with vegetable stock and simmer, partially covered, until very tender, about 20 minutes. Add everything to a blender along with the spices, and whirl until smooth. While the blender is running, slowly pour in olive oil to emulsify.
Store any leftovers airtight in the refrigerator.
