1) Spray the insert of the slow cooker 2) Add the bread pieces to the slow cooker (*if you don't have stale bread, spread the bread cubes on a baking sheet and bake for 10 minutes until browned.) F) 3) Heat the olive oil on medium in a large sauté pan 4) Add the bacon / pancetta pieces and sizzle gently for 3 minutes 5) Add the leeks & mushrooms to the bacon and soften for a further 3 minutes 6) Transfer the mixture to the slow cooker 7) Pour the sherry over the bread; add the tarragon, Provencale blend, salt and stir 8) In a large bowl or jug whisk the eggs; stir in the cream, broth and 1 cup of the Gruyère 9) Pour the egg mixture over the ingredients in the slow cooker 10) Stir, cover and cook on HIGH for 2 hours or LOW for 4 hours 11) Remove the lid, add the remaining 1/2 cup Gruyère & pop under a broiler until the cheese bubbles