Add 10 cups water and 2 tsp salt to a large pot (use same for 4 ppl). Cover and bring to a boil over high heat. Meanwhile, cut tomato into ¼-inch pieces. Peel, then cut half the onion (whole onion for 4 ppl) into ¼-inch slices. Peel, then mince or grate garlic. Roughly chop spinach.

Pat chicken dry with paper towels. Season with half the Italian Seasoning, half the garlic salt and ¼ tsp (½ tsp) pepper. Heat a large non-stick pan over medium-high heat. When the pan is hot, add ½ tbsp (1 tbsp) oil, then chicken. Cook until golden-brown, 1-2 min per side. (NOTE: Don't overcrowd the pan; cook in 2 batches if needed.) Transfer to an unlined baking sheet. Bake in the middle of the oven until cooked through, 5-6 min.**

Meanwhile, add linguine to the boiling water. Cook uncovered, stirring occasionally, until tender, 10-12 min. Reserve ½ cup (1 cup) pasta water, then drain.

Meanwhile, reheat the same pan (from step 2) over medium. When the pan is hot, add 2 tbsp (4 tbsp) butter, then onions and garlic. Cook, stirring often, until onions soften, 3-4 min. Add spinach, tomato, remaining Italian Seasoning and remaining garlic salt. Cook, stirring often, until spinach wilts, 1-2 min.

Add cream, Cream Sauce Spice Blend, sour cream and reserved pasta water to the pan with veggies. Cook, stirring frequently, until sauce thickens slightly, 1-2 min. Season with salt and pepper. Add linguine to the pan with sauce. Cook, stirring often, until coated, 1 min.

Divide linguine between bowls, then top with chicken. Sprinkle Parmesan over top.