Preheat a deep skillet to medium-high heat with the sausage for the sauce. Cook the sausage for 7 minutes or so, breaking it up with a spoon as you go, until crumbly and brown. Add the onion, mushrooms, bell pepper, and carrot to the sausage with a drizzle of olive oil and a sprinkle of salt.
Stir the veggies into the sausage and cook for about 5 minutes, stirring, to soften the veggies slightly. Add the tomato paste and garlic and cook for two minutes more.
Add the canned tomatoes and sugar to the skillet, breaking up the tomatoes with a spoon or your hands as you stir. Taste the sauce and add salt or a bit more sugar to your taste.
At this point, you can simmer the sauce on medium-high for 15-20 minutes, give or take, or on low for lots longer to thicken and reduce the sauce; it all depends on when you'd like to eat.
About 10 minutes before you'd like to eat, taste the sauce again and add more salt and sugar to your preference. Preheat a large skillet to medium-high heat with a drizzle of olive oil until very hot.
When the oil in the skillet shimmers, add the zoodles in one layer and sprinkle with the salt, onion powder, and garlic powder. Toss the spiralized zucchini for 90 seconds until just barely cooked, then remove the skillet from the heat.
Serve the zoodles topped with the sausage sauce and parmesan, if desired. Enjoy!
Whole30 if you omit the sugar from the sauce and don't use parmesan.