Prepare the Ingredients: Cook the whole wheat spaghetti according to package instructions until al dente, then set aside. Spiralize the zucchini into noodles and set aside as well.
Mix the Cornstarch and Milk: In a small bowl, combine the egg yolks, and cornstarch with the skim milk. Stir until the cornstarch is completely dissolved to avoid lumps.
Sauté the Onion and Turkey Ham: Heat the olive oil over medium heat in a large skillet. Add the finely chopped white onion and sauté until it becomes translucent, about 3-4 minutes. Add the diced smoked turkey ham and cook until the pieces are lightly browned and crispy, about 5-6 minutes.
Combine and Cook: Reduce the skillet heat to low. Slowly pour the egg mixture into the skillet with the sautéed onions and turkey ham. Stir continuously to prevent the eggs from curdling. As the mixture heats, it will start to thicken.
Add the Spaghetti and Zucchini Noodles: Once the sauce begins to thicken, add the cooked whole wheat spaghetti and raw zucchini noodles to the skillet. Toss everything together to ensure the noodles are well-coated with the sauce. Continue to cook on low heat for 2-3 minutes, just until the zucchini noodles are slightly tender but still crisp.
Adjust Seasoning and Serve: Taste the pasta and adjust the seasoning with additional salt and pepper if needed. If you prefer a richer flavor, sprinkle with grated Parmesan cheese. Serve immediately to enjoy the creamy consistency of the carbonara.