Whisk egg yolks, finely grated Parmigiano-Reggiano, and 15 ml of heavy cream together in a bowl until a uniform, glossy emulsion forms; set aside at room temperature.

Cook bacon lardons in a cold deep skillet or wok over medium heat until browned and crisp, allowing the savory pork fat to render fully; remove half the bacon for garnish.

Drop heat to medium-low, add minced garlic and gochujang to the rendered bacon fat, stirring constantly for 60 seconds to toast the paste and mellow raw pungency.

Pour in remaining heavy cream, butter, and 60 ml of hot udon cooking water, stirring gently until a smooth, vibrant vermilion simmer emerges.

Drop parboiled udon noodles directly into the simmering sauce, tossing continuously for 1 to 2 minutes so the thick wheat strands absorb the spicy glaze.

Turn off heat completely and allow pan to rest 30 seconds; vigorously stir in the egg yolk-cheese mixture until an ultra-creamy, glossy carbonara coat blankets every noodle.