Heat a non-stick pan over medium heat. Add diced spam and cook until golden and crispy on all sides. Remove from the pan and set aside.
In a small bowl, whisk together the egg yolks, Parmesan, black pepper, and miso paste until it forms a smooth paste. Set aside.
In the same pan, add the shallots and garlic and sauté until fragrant and softened. Remove from heat.
DO NOT salt your water and cook the udon according to package instructions. Reserve 50ml of noodle water before draining.
Add the hot udon noodles and reserved water back to the pan with the garlic and shallots (if using). Off the heat, stir in the carbonara sauce, mixing continuously until creamy and emulsified.
Plate the noodles, top with crispy spam, and (if you're feeling fancy) an extra egg yolk for good measure. Crack it open and mix it in at the table.
