Step 1: Bring about 2-3 cups of water to a boil in a small pot. Once boiling, add the Buldak ramen noodles and cook for 2-3 minutes, or until al dente. Reserve about 1/2 cup of the starchy noodle water, then drain the remaining water from the noodles.
Step 2: While the noodles are cooking, prepare your carbonara mixture. In a small bowl, whisk together the egg yolk (and whole egg, if using), grated Parmesan cheese, and milk (if using). Set aside.
Step 3: Return the drained noodles to the empty pot over low heat. Add the liquid Buldak sauce packet (adjust to your spice preference; use less for milder heat). Stir well to coat the noodles evenly with the spicy sauce.
Step 4: Immediately remove the pot from the heat. Add 2-3 tablespoons of the reserved hot noodle water to the noodle mixture, stirring constantly. This helps to create a saucy base and cool the noodles slightly.
Step 5: Quickly pour the egg and cheese mixture into the noodles. Using tongs or chopsticks, toss vigorously and continuously for about 30 seconds to 1 minute. The residual heat from the noodles and pasta water will gently cook the egg mixture, creating a creamy, glossy carbonara sauce without scrambling the eggs.
Step 6: If the sauce is too thick, add another tablespoon or two of the reserved noodle water until you reach your desired consistency. Stir in the dried vegetable flakes packet from the Buldak ramen package.
Step 7: Transfer the creamy carbonara buldak ramen to a serving bowl. Garnish with extra grated Parmesan cheese, toasted sesame seeds, and fresh chopped green onions, if desired. Serve immediately and enjoy your spicy and creamy carbonara buldak ramen recipe!