Preheat oven to 400F.
Grease a 2-quart baking dish with cooking spray and set aside.
Heat half tablespoon olive oil in a large nonstick skillet over medium-high heat.
Add turkey sausage to the skillet and cook for 4 to 5 minutes, or until browned.
Remove sausage from pan, drain, and set aside.
Return skillet to heat and add remaining olive oil.
Add onions and cook for 2 minutes.
Stir in mushrooms and garlic and continue to cook for 5 to 6 minutes, or until mushrooms are soft.
Add potatoes, thyme, salt and pepper; cook for 5 minutes or until potatoes have browned.
Stir in sausage and broth and remove from heat.
Transfer the mixture to previously prepared baking dish.
Top with cheese and cover.
Bake for 30 minutes.
Remove aluminum foil and continue to cook for 12 to 15 minutes, or until golden brown.
Remove from oven and serve.