Melt butter in a large Dutch oven or heavy-bottomed pot over medium; cook onions 25-30 minutes, stirring occasionally, until deeply caramelized and golden brown.
Add garlic; cook 1 minute until fragrant.
Sprinkle flour over onions; stir to coat and cook 2-3 minutes to remove raw flour taste.
Gradually whisk in broth, breaking up lumps.
Stir in paprika, cayenne, garlic powder, black pepper, and onion powder.
Simmer gently 10 minutes to meld flavors.
Stir in cream; simmer another 5 minutes and salt to taste.
Serve hot topped with crispy fried onions and fresh chives.