Heat oil in a 10-inch non-stick skillet set over medium heat.
Add the mushrooms and cook, stirring occasionally until they give off their liquid, liquid comes to a simmer, then reduces to a glaze, about 4 minutes.
Stir in the tomato, thyme, salt, rosemary, and pepper; cook 20 seconds, until aromatic. Pour in egg substitute or eggs, making sure the vegetables are evenly distributed, and sprinkle the Parmesan cheese over the top.
Cover, reduce heat to low, and cook until set about 12 minutes. Cut into six wedges & serve.
Note: You can brown the top of the frittata. Preheat the broiler while the frittata is cooking. Once set, broil it for about 20 seconds, five inches from the heat source, just until the top is slightly browned.