Looks like the card got a bit stained.
Fortunately, the card cites the White House Cook Book (by Fanny Lemira Gillette) as its source. So let’s peek at this recipe in the 1887 edition:
Apple omelet, to be served with broiled spare-rib or roast pork, is very delicate. Take nine large, tart apples, four eggs, one cup of sugar, one tablespoonful of butter; add cinnamon or other spices to suit your taste; stew the apples till they are very soft; mash them so that there will be no lumps; add the butter and sugar while they are still warm; but let them cool before putting in the beaten eggs; bake this till it is brown; you may put it all in a shallow pudding-dish or in two tin plates to bake. Very good.
J.L. must’ve had a later edition, because this recipe shows up on page 144. Which makes sense, because even in this edition, page 97 has a similar recipe, Yorkshire pudding, which is to beef what the apple omelet is to pork:
This is a very nice accompaniment to a roast of beef; the ingredients are, one pint of milk, four eggs, white and yolks beaten separately, one teaspoonful of salt, and two teaspoonfuls of baking powder sifted through two cups of flour. It should be mixed very smooth, about the consistency of cream. Regulate your time when you put in your roast, so that it will be done half an hour or forty minutes before dishing up. Take it from the oven, set it where it will keep hot. In the meantime have this pudding prepared. Take two common biscuit tins, dip some of the drippings from the dripping-pan into these tins, pour half of the pudding into each, set them in the hot oven, and keep them in until the dinner is dished up; take these puddings out at the last moment and send to the table hot. This I consider much better than the old way of baking the pudding under the meat.
Compare this version from the October 31, 1914 edition of The Fort Wayne (Indiana) Sentinel:
To eight large apples stewed very soft and mashed fine add one cup of sugar and flavor with nutmeg or cinnamon. When cold stir in three well-beaten eggs and one-half tablespoon cornstarch dissolved in two tablespoons of milk. Stir well and bake slowly twenty minutes. Serve hot.
From the box of J.L. from Westborough, Massachusetts.
9 large tart apples
1 cup sugar
1 Tbsp. butter
cinnamon or other spices]
Take 9 large tart apples, 4 eggs, 1 cup sugar; 1 Tbsp. of butter–add cinnamon or other spices to suit your taste–stew the apples till they are soft–mash them so they are still warm–but let them cool before putting in the beaten eggs–bake this till it is [brown; you may put it all in a shallow] pudding-dish [or in two tin plates.]
White House Cook Book, p. 97