Bring a large saucepan of salted water to a boil. Add in the trimmed sprouts and cook for 8 minutes. Drain and cut in half.
Wipe out the skillet and add in the bacon and shallots. Cook until the bacon is the crispy and the shallots are soft with golden edges. Use a slotted spoon and transfer to a plate.
Place the halved Brussels sprouts in the buttered baking dish, sprinkle with salt and pepper and scatter the bacon and shallots over top.
Next, pour in the cream, top with the grated cheddar and breadcrumbs. Dot with remaining tablespoon and a half of butter and bake in preheated 350 degree oven for 20 minutes, or until bubbly and golden.