Skillet Sausage Stew
Using a large, deep skillet, brown your sausage over medium heat. If using sausage meat, break up with the back of a spoon into crumbles, then remove from pan and put aside. If using links, brown evenly and also set aside until cool enough to slice.
Remove any extra grease from the pan other than what is needed to saute the onions, if necessary. Add them to the pan over a low-medium heat and soften slightly before adding the zucchini slices.
Saute for a few minutes before adding the mushrooms.
Add the tomato sauce, fennel seeds, Italian seasoning and garlic powder.
Add the sausage back to the pan; slice links first if using.
Bring almost to a boil, then cover (with a little gap to let steam escape).
Turn the heat to low and let simmer for 15 minutes or until the vegetables release their juices.
Uncover the pan and add red pepper flakes to taste.
Let the stew simmer about 10 minutes until it is slightly thickened, then add spinach leaves to wilt before serving.