Before starting, wash and dry all produce. 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. Add linguine to the boiling water. Cook uncovered, stirring occasionally, until tender, 10-12 min. Drain and return linguine to the same pot, off heat.

Meanwhile, peel, then finely chop shallot. Thinly slice mushrooms. Rough chop spinach.

Heat a large non-stick pan over medium-high heat. When hot, add 1 tbsp butter (dbl for 4 ppl), then swirl the pan until melted. Add shallots. Cook, stirring often, until softened, 2-3 min. Add mushrooms and 1/4 tsp garlic salt (dbl for 4 ppl). Cook, stirring occasionally, until mushrooms begin to soften, 2-3 min. Add soy sauce. Cook, stirring often, until mushrooms are tender, 2-3 min. Season with pepper.

Reduce heat to medium. Stir cream cheese into mushroom mixture. Cook, stirring often, until cream cheese melts, 1-2 min. Add cream. Cook, stirring often, until sauce thickens slightly, 2-3 min. Add spinach. Stir until wilted, 1-2 min. Season with 1/4 tsp garlic salt (dbl for 4 ppl) and pepper.

Pour mushroom Alfredo sauce into the pot with linguine, then toss to combine.

Divide mushroom Alfredo between bowls. Sprinkle with Parmesan. Sprinkle chili flakes over top, if desired.