Eight minutes, three eggs, and the pan temperature almost everyone gets wrong. A breakfast with real protein in it, which most British breakfasts are not.

The point of this breakfast is that it contains protein, which the usual British alternatives do not.
Toast and cereal deliver carbohydrate with almost no protein, so appetite returns within two hours. Three eggs and feta bring about 27g, which is in the range most people need per meal to hold appetite steady through the morning.
Eggs also supply cholesterol and saturated fat, and both are substrates for steroid hormone synthesis. That does not mean eating more eggs raises testosterone — the body regulates production tightly, and the relationship is not a dial. It means that very low-fat diets have been associated with lower testosterone in men, and that a breakfast containing fat is not the problem it was once assumed to be.
Pumpkin seeds are here for zinc, the one mineral with an authorised claim attached to the maintenance of normal testosterone levels in the blood. One tablespoon is not a large dose, but it is a daily habit rather than a supplement, which is usually the better bet.
Spinach adds magnesium and dietary nitrate, and it cooks down to almost nothing, so 60g is less than it sounds.
More on why the first meal matters: breakfast mistakes that work against testosterone.