In a large skillet, cook the bacon over medium-low heat until the bacon is crispy. Remove the bacon from the pan and transfer to a plate. Drain all but 1 tablespoon of the bacon fat. Add the butter and pepper to the pan and cook over medium heat for 1 minute.

Cook the udon noodles in a pot of boiling water, according to package directions, about 3-5 minutes. Reserve 1/2 cup of the water. Drain the noodles and add to the pan while still hot. In a small bowl, whisk together the eggs, yolks, heavy cream, and cheese. While whisking, pour in the reserved pasta water until the sauce is smooth.

Pour into the pan over the noodles, and stir constantly over medium-low heat, until the sauce is warmed through and thick. 

Return the bacon to the pan and season to taste with salt. Serve immediately topped with chives or green onions and extra parmesan.