If you have eggs and bread
Soft scrambled eggs on toast with butter and flaky salt. Or upgrade: shakshuka if you've got canned tomatoes; French toast if you've got milk and a little sugar.
If you have eggs and tortillas
Breakfast tacos. Scramble eggs soft, pile into a warm tortilla with cheese, hot sauce, and anything else (beans, avocado, leftover roasted vegetables). 8 minutes.
If you have oats and milk
Stovetop oatmeal cooked in milk with a pinch of salt, topped with brown sugar and butter. The salt and butter are non-negotiable. Add fruit if you have it.
If you have leftover rice
Korean-style breakfast bowl: warm rice, fried egg, kimchi (or any pickle), sesame oil, soy sauce. Five minutes, deeply satisfying.
If you have yogurt
Bowl with honey, olive oil (yes, really), and any nuts or seeds. Or blend into a smoothie with frozen banana and peanut butter.
If you have time on the weekend
Dutch baby pancake: blend 3 eggs, 1/2 cup flour, 1/2 cup milk, pour into a hot cast-iron skillet with butter, bake at 425°F for 18 minutes. Looks like effort, takes none.