In a 12-inch non-stick, oven proof skillet, heat 1 teaspoon of the oil over medium high heat and cook sausage, green onions and garlic, breaking up with a spoon, for 3 minutes. Stir in apple, fennel (if using) and nutmeg; cook, stirring for about 4 minutes or until sausage is no longer pink and apples are tender crisp. Scrape into a bowl; set aside.
Return skillet to medium low heat and add remaining 1 teaspoon oil.
In a separate bowl, whisk together eggs, water and pepper. Pour into skillet and cook, stirring gently until eggs start to set. Place under the broiler for 3 minutes or until eggs are completely set and puffed. Slide the omelette onto a serving platter and spread sausage mixture on half of the omelette. Fold remaining half over sausage filling to cover.