Spread the English muffin cubes evenly on a baking sheet to dry out overnight. Alternatively, toast them briefly under the grill until just crisp.

Grease a 32 × 20 cm baking dish. Layer half of the dried muffin cubes, half of the ham, and half of the cheddar cheese. Repeat the layers.

In a large bowl, whisk together the half and half, eggs, salt, pepper, mustard powder, garlic, onion powder, thyme, and nutmeg until smooth.

Pour the custard mixture over the layered ingredients, pressing muffin cubes gently to absorb the custard. Cover and refrigerate overnight.

Preheat the oven to 175°C (350°F). Remove from the fridge 15 minutes before baking. Dot with butter and sprinkle with paprika. Cover with foil and bake for 30 minutes, then remove foil and bake for another 15-20 minutes until golden.

Prepare hollandaise sauce while the casserole bakes. Follow your preferred method.

Let the casserole rest for 5 minutes after baking. Drizzle with hollandaise sauce and garnish with chives or parsley before serving.