Sort and rinse 1 pound dried pinto beans under cold running water to remove any debris.

Place the rinsed beans in a large bowl, cover with cold water by 3 inches, and soak for at least 4 hours or overnight.

Drain the soaked beans and set aside. Heat a large heavy-bottomed pot over medium-high heat and add chopped bacon. Cook for 5 to 7 minutes until crispy and fat is rendered.

Remove bacon with a slotted spoon and leave 2 tablespoons of bacon fat in the pot. Add diced onion and cook for 3 to 4 minutes until translucent, then stir in minced garlic and cook for 30 seconds until fragrant.

Stir in drained beans, ham hock, and reserved bacon. Add 6 cups stock, 2 bay leaves, 1 teaspoon smoked paprika, 1 teaspoon salt, 1/2 teaspoon black pepper, and 1/4 teaspoon red pepper flakes if desired.

Increase heat to high and bring to a rolling boil, about 10 minutes. Skim off any foam that rises to the surface using a skimmer.

Reduce heat to low, stir in 2 tablespoons butter, cover with the lid slightly ajar, and simmer gently for 90 minutes to 2 hours until beans are fork-tender.

Remove ham hock and bay leaves. Taste and adjust seasoning with additional salt and pepper as needed before serving.