2.Heat oil in a large non-stick frying pan over medium heat, cook bacon 1½ minutes each side or until golden. Drain on paper towel.
3.Cut croissants horizontally three-quarters of the way through, keeping the two sides still attached. Fill croissant evenly with bacon and cheddar, press gently together to close. Place croissant sandwiches close together in a 23cm x 34cm x 6cm (9¼-inch x 13½-inch x 2½-inch) ovenproof dish.
4.Whisk cream, eggs and gruyère in a medium jug until combined, season. Pour cream mixture gently over croissants, stand 5 minutes or until cream has soaked into croissants slightly.
5.Bake croissants for 20 minutes or until golden and cheese melts. Serve immediately topped with thyme and mustard.
You can double or triple the quantities, filling large dishes to serve a crowd. Do ahead This recipe can be prepared a day ahead to the end of step 3, cover and refrigerate. Finish the recipe when you’re ready to serve. Substitutes You can use a combination of other cheeses such as parmesan, vintage cheddar, edam, mozzarella or brie. This moreish recipe is a play on the french classic, croque monsieur, which uses bread rather than the croissants, we’ve used here.