01 - Bring a large pot of generously salted water to a rolling boil. Add the pasta and cook until al dente, following package directions. Before draining, carefully reserve 200 milliliters of the starchy pasta cooking water.
02 - In a mixing bowl, thoroughly whisk together the egg yolks, whole egg, grated Parmesan cheese, white miso paste, mashed black garlic, heavy cream (if using), and a liberal amount of freshly ground black pepper until a smooth, cohesive mixture is formed.
03 - While the pasta is cooking, heat the olive oil in a large skillet over medium heat. Add the diced pancetta (or smoked tofu for a vegetarian alternative) and cook until it becomes crisp and golden brown, approximately 3–4 minutes. Introduce the minced garlic to the skillet and sauté for about 30 seconds until it becomes fragrant. Remove the skillet from the heat.
04 - Add the drained pasta directly into the skillet containing the rendered pancetta and garlic oil. Toss thoroughly to ensure the pasta is evenly coated.
05 - Ensure the skillet is removed from direct heat. Immediately pour the prepared egg-miso mixture over the hot pasta. Toss vigorously and continuously to create a silky, emulsified sauce. Gradually incorporate the reserved pasta cooking water, a small amount at a time, as needed, until the sauce achieves a luxurious, creamy consistency that coats the pasta beautifully.
06 - Divide the Miso Carbonara evenly among serving bowls. Garnish generously with finely sliced chives or green onions and an ample dusting of extra grated Parmesan cheese. Serve with utmost immediacy.