Savoury omelet for Two Persons

Food in England, Dorothy Hartley, p. 214

'An omelet is a friendly dish - the friends must be seated and have wine or coffee served to them, so that they await cheerfully. Never cook the omelet till you have seen the recipient seated, with his napkin tucked down, ready to begin.' p. 213

Suggested fillings: chopped mushroom, shreds of chicken and ham, fresh chopped herbs for plain fillings; crisp bacon and fine onions for winter, green peas and asparagus for summer. 'Fillings should be slight, but very well flavoured and juicy.'
Sweet omelet: flavoured with rum or sherry (instead of water? Or just a sprinkle?) with a fruit or jam filling. Honey and cinnamon with a sprinkle of hot cider on the folded top

2 large mushrooms, chopped
1 slice bacon, diced
1 Tbsp butter
3 eggs
1/4 tsp fresh herb(s)
Dash of salt and pepper

1. In a large oven-ready non-stick or well-seasoned cast iron pan, slowly fry the mushrooms and bacon in the butter.
2. Meanwhile, separate the egg whites and whisk just until soft peaks barely form.
3. Using the egg shells, measure out three egg-shell halves of water and add to the yolk, one for each egg. Add a dash of salt and pepper.
4. Without wiping the whisk used to whip the whites, beat the yolks - 'they should raise a fine froth'.
5. Once the filling is well cooked, remove it with a slotted spoon and keep it piping hot.
6. Turn on the broiler of your oven.
7. When the butter is once again smoking hot (add more if necessary, depending on filling), lightly mix together the yolk and whites and immediately pour the egg into the hot pan. 'It should make a delicious frou-frou soundas it greets the hot butter, and the top of the foam should quiver delicately.'
8. Immediately put it under the broiler. The golden froth should start to expand upwards. If you like the centre a little runny, remove it in __ minutes or when __??__. If you prefer it cooked through cook __ minutes. In either case, the edges should come away from the pan.
9. Slide it onto a hot dish, put the filling on one half 'folding it over in one swift movement. Serve instantly.'