Bring a large pot of salted water to a boil. Add the spaghetti and cook according to the package instructions until al dente. This usually takes about 8-10 minutes.
While the spaghetti is cooking, heat a large skillet over medium heat. Add the room-temperature butter and let it melt gently. Once melted, add the minced garlic and sauté for about 1-2 minutes, or until fragrant but not browned.
To the melted butter and garlic, add the oyster sauce, Sriracha hot sauce, and sugar. Stir well to combine and let it simmer for another minute to meld the flavors together.
Once the spaghetti is cooked, reserve about 1/2 cup of the pasta water and then drain the rest using a colander.
Add the drained spaghetti directly to the skillet with the sauce. Toss the noodles in the sauce, ensuring they are well coated. If the mixture seems dry, add a splash of the reserved pasta water until you reach your desired consistency.
Once the noodles are well coated and heated through, remove from heat. Serve the Garlic Sriracha Noodles in bowls, topping each serving with a sprinkle of grated Parmesan cheese and a generous handful of chopped scallions for a fresh finish.
