Bring a medium pot of generously salted water to a boil. Use just enough water for the spaghetti to cook comfortably*. Add the spaghetti and cook until al dente, stirring occasionally to prevent sticking. Before draining, reserve about 1 cup of the cloudy, starchy pasta water.
Meanwhile, melt the butter in a large skillet over medium heat. Add the minced garlic and shallot and cook for about 2–3 minutes, stirring frequently, until the shallot has softened and the garlic is fragrant. Do not allow the garlic to brown. Stir in the garlic powder, onion powder, and all-purpose seasoning.
Pour in the chicken stock and only 1/2 cup of the reserved starchy pasta water. Increase the heat to medium-high and bring the mixture to a gentle boil.
Add the lemon juice and the al dente spaghetti (I just transfer it from the boiling pot into the pan sauce without draining).
Using tongs, toss continuously in the sizzling sauce for about 2–3 minutes, or until the pasta is tender and the liquid has reduced into a glossy sauce that evenly coats the noodles. If the sauce reduces too quickly, add another splash of extra reserved pasta water as needed.
Reduce the heat to low. Add the parsley and Parmesan, and toss just until the cheese melts into the noodles. Taste and season with salt and freshly cracked black pepper as needed.
Serve immediately topped with additional freshly grated Parmesan.
For Spicy Garlic Butter Noodles: Add 1 tablespoon chili crisp to the sauce, increasing to taste. Substitute fresh cilantro for the parsley and finish as directed.