Heat olive oil in a large Dutch oven or heavy-bottomed pot over medium-high heat. Add ground beef and cook, breaking it up with a spoon, until browned. Drain any excess fat.

Add chopped onion, carrots, and celery to the pot. Cook until vegetables begin to soften, about 7-8 minutes. Stir in minced garlic and cook for another minute until fragrant.

Add chili powder, cumin, smoked paprika, and cayenne pepper (if using). Stir and cook for 1 minute until spices are fragrant.

Pour in crushed tomatoes, diced tomatoes (undrained), and beef broth. Bring to a simmer, then reduce heat to low, cover, and let it cook for 30 minutes to allow flavors to meld.

Stir in the rinsed and drained black beans and kidney beans. Continue to simmer gently while you prepare the "cookies."

In a large mixing bowl, whisk together flour, baking powder, and salt. Cut in the cold butter using a pastry blender or your fingertips until the mixture resembles coarse crumbs.

Add chopped chives and then pour in 1/2 cup milk. Mix gently with a fork until just combined. Do not overmix. The dough should be shaggy but come together. If too dry, add milk 1 tablespoon at a time.

Increase heat of the soup to a gentle simmer. Using a tablespoon or small scoop, drop dollops of the biscuit dough directly into the simmering soup. They should look like small, rustic cookies.

Cover the pot and cook for 15-20 minutes, or until the "cookies" are cooked through and fluffy. Avoid lifting the lid too often during this time.

Season the soup with salt and black pepper to taste. Ladle the hearty "Cowboy Cookies" soup into bowls and serve hot. Garnish with extra chives or a dollop of sour cream if desired.