Add bacon to a cold 5- to 6-quart Dutch oven. Cook over medium heat for 8–10 minutes until crisp. Transfer to a plate, reserving about 3 tbsp bacon fat in the pot.
Add onion, celery, and bell pepper. Cook for 6–8 minutes until softened. Add garlic and cook for 30 seconds.
Stir in flour and cook for 1 minute. Slowly stir in chicken broth until smooth.
Add potatoes, corn, salt, thyme, pepper, and smoked paprika. Bring to a gentle boil, reduce to a simmer, and cook uncovered for 14–18 minutes until the potatoes are fork-tender.
Reduce heat to low. Stir in milk, cream, 3/4 cup cheddar, about two-thirds of the bacon, and half the green onions. Cook gently for 4–5 minutes without boiling.
Remove from heat and rest for about 5 minutes. Serve topped with reserved bacon, remaining 1/4 cup cheddar, and remaining green onions.