Preheat the oven to its highest setting (250°C).
Blend together all the ingredients for the batter and rest for at least 30 minutes.
Meanwhile, pour enough oil to cover the base of a large roasting tin or oven-proof dish. Heat in the oven and then add the sausages, red onion and lardons. Cook until browned and the oil is smoking hot once again.
Remove from the oven and as quickly as possible, pour the batter mix around the sausages and dot over the Gorgonzola and rosemary. Carefully return to the oven and cook for 25-30 minutes until risen, crisp and golden.
Cook’s tip: Don’t be tempted to open the oven door whilst the dish is cooking, as this will prevent the batter from rising to its full potential.
Recipe courtesy of Gorgonzola