Grease an 8-inch by 8-inch baking dish with a little bit of vegetable oil. Set aside.
Add bacon to a Dutch oven and cook on the stovetop, stirring often, until fat is starting to get released (about 3 minutes on medium-high heat).
4 slices regular-cut bacon, cut into ½-inch pieces
Stir in the Brussels sprouts, then transfer to the oven and roast, uncovered, for 30 minutes, stirring everything around halfway through.
16 small Brussels sprouts, cut into quarters
Meanwhile peel, core, and cut the apple into 1-inch chunks.
1 large honeycrisp apple
Stir the apple chunks into the Brussels sprouts and bacon mix.
Transfer the mix back to the oven and continue to roast until the Brussels sprouts are tender (about another 20 min.) Stir everything around halfway through.
Transfer the mix to a bowl. Turn down the oven temperature to 325 degrees F.
Add the vegetable oil to the Dutch oven (you don't need to clean it first.) Heat the oil until shimmering, then add the bread cubes and the sage and fry just until the sage is starting to lose its bright green color (about 3 minutes).