In a Dutch oven over medium-low heat, cook chopped bacon until crispy and golden, about 8–10 minutes. Remove bacon and let drain while keeping the fat in the pot.

Add sliced red onions to the pot with bacon fat and sauté for about 5–6 minutes until tender. Then, add chopped scallions and a pinch of salt. Set aside, then add halved Brussels sprouts, browning them for about 5 minutes until tender.

In the same pot, toss in the chopped kale and wilt it for just a minute or until bright green. Set aside with previous vegetables.

Pulse bread slices in a food processor until coarse crumbs. In a skillet over medium heat, sauté breadcrumbs with reserved crispy bacon until golden brown, about 3–4 minutes.

Bring salted water to a boil and cook conchiglioni pasta for about 7–8 minutes until slightly under al dente. Drain, reserving some cooking water.

In the same Dutch oven, melt butter over medium heat. Whisk in flour and gradually add heated milk, stirring until thickened, about 5 minutes. Stir in cheddar cheese until smooth.

Add drained pasta and all vegetables to the cheese sauce, mixing gently until well-coated. Adjust seasoning as needed.

Serve in bowls topped with crispy bacon breadcrumbs and chives for freshness.