Preheat the oven to 350 degrees. Coat a 9x12 glass baking dish with butter or vegetable oil.
Toast the pecans in a single layer on rimmed baking sheet in the oven for 15 minutes. Set aside.
Cut the bread into 1-inch cubes and layer evenly in baking dish. Sprinkle blueberries on top.
Combine the eggs, half & half, sugar, vanilla, and cinnamon in a blender for about 5 seconds. (If mixing in a stand mixer, beat for 2 minutes on medium-high.) Pour the mixture over bread.
For the topping, combine the butter, sugar, and corn syrup in a mixing bowl outfitted with a paddle and mix on medium-high until creamy, about 2 minutes. Fold in the toasted pecans, oats, and nutmeg and mix just to combine.
Dollop and carefully spread the topping onto the top of the bread. Cover with foil and refrigerate overnight.
Bring the dish to room temperature before baking. When ready to bake, preheat the oven to 375 degrees.
Place the dish over a rimmed baking sheet as this will drip when baking (oven fires are not a good thing, learn from my mishaps!).
Bake covered in foil for about 40 minutes. Remove the foil and bake for another 10 minutes. Reduce the oven to 275 degrees and let sit in oven for another 10 minutes.
Remove from oven and let rest for 10 minutes before slicing (very important to let it rest before slicing or it will not hold its shape). Slice down the middle of the pan, then into 4 or 5 slices across.
Drizzle the warm Maple-Rum Sauce over the top of each slice and serve with fresh sliced peaches and blueberries.
Maple Rum Sauce
1 ½ cup heavy cream
⅓ cup packed dark brown sugar
¼ cup maple syrup
⅓ cup spiced rum
3 tsp cornstarch
For the Maple-Rum Sauce: Combine the cream, sugar, maple syrup, and ⅓ cup rum in a medium saucepan and bring to a slow boil over low heat. Dissolve the corn starch in the remaining 3 tablespoons of rum. Whisk in the cornstarch mixture, lower the heat, and cook for another 2 minutes, until thickened. Remove from the heat and serve warm. When cool, store in the refrigerator for a few days or freeze for up to 3 weeks. Simply reheat in the microwave on low to warm.
Recipe from The Art of Breakfast by Dana Moos/Down East, 2011.