(Preheat the oven to 200°F if making multiple omelets and store the cooked omelets on a baking sheet in the oven until all are finished.)
Heat oil in a nonstick pan on low medium heat. Sauté the mushrooms until soft. In the meantime, toast the bread.
Pour the eggs into the pan. As the eggs set around the edge of the pan, with a spatula, gently lift the egg to allow uncooked egg to flow underneath. When eggs are almost set on the surface but still look moist, add the cheese and chives. Slip the spatula under the omelet and fold over.
In a nonstick pan, brown the chicken sausage on both sides.
Serve the omelet with toast, chicken sausage and sliced banana.