Halve four muffins and place under a hot grill for 2-3 minutes, until lightly toasted. Lay 3 slices of chorizo over each muffin half and grill again for 1 minute.
Meanwhile, poach 8 eggs in a pan of simmering water; drain on kitchen paper. Gently heat 2 packs hollandaise sauce in a pan for 1-2 minutes, whisking constantly until warm and smooth. Serve the eggs on the muffins, spooning over the sauce and grinding over a little black pepper