Cut the top off your bread loaf. Tear out the bread from the middle. Spread some mayonnaise in the bowl of the bread, then go in with a layer of cheddar.
Top with bacon and chicken, then another layer of cheese. Spread on some more mayonnaise, then top with a layer of peppers, spinach and a final layer of cheese. A final lick of mayo then top with the bread lid.
Wrap well in foil. Weigh down overnight in the fridge under something very heavy.
Remove the weights, then cut the sandwich into 4 pieces. Piece the sandwich back together (foil still on) and bake for 30 minutes at 180°C, until hot through and a bit melty.