Cook bacon in a large skillet over medium heat for about 10 minutes, until bright in color. Remove bacon from skillet, reserving the bacon grease.
Add garlic, red onion, zucchini, and mushrooms to the pan. Cook until soft, about 10 more minutes on medium heat. Add wine and cook for 2 minutes. Now add bacon back, mix, and turn the heat down to low.
In a medium bowl, whisk together eggs, heavy cream, and ⅔ cup of Parmesan. Pour into the pan and combine with the vegetables. Cook on low heat for 5 minutes. Season with salt and pepper to taste and mix.
Add spinach and allow it to wilt.
Meanwhile cook spaghetti according to package directions in salty water. Reserve 1 cup of pasta water.
Turn off heat and add cooked spaghetti into the skillet. Coat in the sauce and add pasta water to thin the sauce. Start with ½ cup. Serve in shallow bowls with remaining ⅓ cup of grated parmesan cheese.