Preheat a large, nonstick skillet over medium-high heat with 2 turns of the pan of EVOO, about 2 tablespoons. Add in the sliced andouille and cook until crisp and golden brown. Remove to a paper towel-lined plate to drain excess fat.
Generously butter a 9x13" casserole dish. Toss the andouille with the torn bread and sliced peaches, and place the mixture into the casserole dish.
In a large mixing bowl, combine the eggs, milk, half-and-half, vanilla, nutmeg and salt, and whisk until blended. Pour over the bread and sausage mixture, making sure it's covered evenly with the milk-egg mixture. Cover with foil and place in the refrigerator overnight.
The next day, preheat oven to 375F. Bake for 40 minutes, until puffed and lightly golden.
While the French toast is baking, mix the marmalade with Dijon, lemon zest and juice in a large mixing bowl. Drizzle the EVOO in a slow and steady stream, whisking until combined. Season with salt and ground black pepper and toss in the orange slices and Bibb lettuce. Serve the salad alongside the baked French toast with the maple syrup passed at the table.