1 loaf (about 13 oz) day old bread
2 cups milk
6 oz bacon
1 bulb fennel
1 Granny Smith apple
1 bunch thyme, roughly chopped
1 cup freshly grated parmesan plus extra for topping
Salt and freshly ground pepper
Cut the bread into 1-inch cubes. If the bread is not yet stale, spread the pieces onto a baking sheet and toast at 350°F. Butter a 3-quart baking dish and set aside
Chop the fennel and apple into 1/2-inch pieces. Cut the leek in half lengthwise and chop the halves crosswise into half moons, about 1/4 inch thick.
Slice the bacon crosswise into 1/4-inch pieces. In a large sauté pan, cook over medium heat until crispy. Using a slotted spoon, transfer the bacon pieces to a paper towel-lined plate, reserving about 2 tablespoons of the bacon fat.
To the same pan with the bacon fat, add the fennel, leeks and a pinch of salt and pepper. Cook until starting to soften, about 2-4 minutes. Then, add the apple and cook a few more minutes until soft. Remove from heat and allow to cool slightly.
In a large bowl, whisk the eggs and milk together with salt and pepper. Add the bread cubes, veggies, thyme and parmesan and toss gently with a wooden spoon until all of the bread is coated. Spread the mixture into the buttered baking dish and top with more parmesan. Cover and chill in the refrigerator for at least 2 hours or overnight.
Preheat the oven to 350°F. Bake for 55-65 minutes, or until puffed and golden.