Preheat oven to 425° F. On a baking sheet, combine the cauliflower, 3 tablespoons olive oil, paprika, oregano, fennel seeds, and a pinch each of salt and pepper. Toss well to evenly coat. Transfer to the oven and roast for 15 minutes, or until tender. Add the 2 cloves garlic and fish sauce. Roast another 10 minutes, until charred.Heat 1/4 cup olive oil in a large skillet over medium-low heat. When the oil shimmers, add the shallot, Fresno, and garlic. Cook until the shallots begin to caramelize, about 5 minutes. Reduce the heat to low, add the tomato paste, cook 4-5 minutes until thickened. Stir in 1/3 cup water, cook another 2 minutes. Stir in the pesto. Season with salt and pepper. Keep warm over low heat.Bring a large pot of salted water to a boil. Add the pasta and cook according to package directions until al dente. Just before draining, remove 1 1/2 cups of the pasta cooking water. Drain.To the sauce, add the pasta, cauliflower, 1/2 cup pasta cooking water, and the butter, tossing until the butter has melted. Add the Parmesan and basil. If needed, thin the sauce with additional pasta cooking water.Divide the pasta among plates and top with basil and cheese. Enjoy!