Cook the Udon Noodles. Bring a large pot of water to a boil. Add the frozen udon noodles and cook according to package instructions. Before draining, scoop out ½ cup of the noodle water and set aside. Drain the noodles, rinse briefly under cold water to stop cooking, and set aside.

Sauté the Aromatics. In a large skillet over medium heat, melt the butter until foamy. Add the minced garlic and finely chopped shallots. Sauté for about 2 minutes, stirring frequently, until the mixture is fragrant and lightly softened.

Cook the Gochujang. Stir in the gochujang and cook for about 30 seconds. This step helps deepen its flavor and mellow out the spice, creating a richer base for the sauce.

Build the Sauce

Slowly pour in the heavy cream, reserved noodle water, soy sauce, and gochugaru. Stir everything together until well combined. Allow the sauce to come to a gentle simmer and cook for 3–4 minutes, or until it thickens slightly. Stir occasionally to prevent sticking.

Toss the Noodles. Add the cooked udon noodles to the pan. Use tongs to toss them in the sauce until every strand is evenly coated and glossy. Cook for another 1–2 minutes to let the noodles absorb the flavors.

Finish and Serve. Transfer the noodles to serving bowls. Top with chopped green onions, freshly grated parmesan cheese, and a raw egg yolk if desired. Stir the yolk into the noodles just before eating for an extra creamy finish. Serve immediately.