Split the remaining butter between two 15 to 18-cm (6 to 7-inch) hot non-stick pans. Pour half the eggs into each pan. Cook over medium heat, breaking the bottom of the omelet with a spatula to facilitate cooking. Season with salt and pepper. When the edges of the omelet - and not the centre - are almost cooked, sprinkle with the cheese. Add the apples on one half of each omelet, then the nuts. With a spatula, fold the other side of each omelet over the filling and slide onto a plate. Garnish with chives and serve with crisp spicy bacon.