Preheat oven to 375 degrees F. Heat oil in large skillet over medium heat. Add mushrooms and bell pepper to skillet and cook 3 to 4 minutes or until softened, stirring occasionally. Remove from heat.

Meanwhile, in large liquid measuring cup, whisk eggs until well beaten. Whisk in milk, parsley, salt, pepper and nutmeg.

Liberally spray a 12 cup standard muffin pan with cooking spray. Divide vegetable mixture between prepared muffin cups. Divide bacon and cheese evenly over vegetables, then pour egg mixture evenly over all of the cups.

Transfer to oven and bake 14 to 16 minutes or until eggs are set. Transfer pan to wire rack and let stand 5 minutes. Run small knife around outside of each cup to remove muffins. Serve immediately, or transfer muffins to wire rack and let cool completely, then transfer to zip-top bags and refrigerate or freeze for later use. 

Muffins can be refrigerated for up to 3 days or frozen up to 1 month. Muffins can be re-heated in microwave straight from refrigerator or freezer. Place on microwave-safe plate and microwave 30 to 45 seconds or until heated through.