Preheat the oven to 375°F (190°C). Lightly spray a glass casserole dish (approximately 18 x 28 cm / 7 x 11 inches) with nonstick spray.

Cut the broccoli into bite-sized florets, about 2–3 cm (1 inch) across.

Place the broccoli in a pot, cover with water, and bring to a boil. As soon as the water boils and the broccoli turns bright green (less than 5 minutes), drain immediately in a colander.

While the broccoli cools slightly, crack the eggs into a large mixing bowl. Add the cream or milk, seasoning, and black pepper. Beat well until fully combined.

Spread the well-drained broccoli evenly in the prepared casserole dish. Sprinkle the Swiss, mozzarella, and cheddar cheeses over the broccoli.

Pour the egg mixture over the broccoli and cheese. Use a fork to gently stir so everything is evenly distributed.

Bake for about 25 minutes, or until the eggs are set, puffed, and the top is lightly golden.

Remove from the oven and let rest for a few minutes before slicing and serving.