Preheat oven to 425 degrees F. Line a baking sheet with aluminum foil. Toss chopped cauliflower with salt, pepper and olive oil, then place on the baking sheet. Roast for 20-30 minutes, tossing 2-3 times during cooking, until charred and crispy.
While cauliflower is roasting, prepare water for pasta, bring to a boil and cook according to directions. On a cutting board, squeeze out roasted garlic cloves and used a fork, mash into a smooth paste.
Place pine nuts in a small saucepan over medium-low heat and cook until toasted and slightly fragrant, tossing with a wooden spoon. This should take about 5-6 minutes. Set aside.
In a large skillet, heat butter oven medium heat and once sizzling, whisk in flour to create a roux. Stir for 1-2 minutes until golden, then add in milk and half/half. Whisk constantly until milk thickens a bit, about 2-3 minutes. Reduce heat and whisk in roasted garlic (paste), cheese and nutmeg. Taste and season with salt and pepper as desired. Toss the pasta in the sauce and using kitchen tongs, toss to coat. Top with crispy cauliflower, pine nuts and chopped herbs. Serve with salmon on the side.