In a pot melt butter and add in diced onion. Sauté over medium heat until tender and translucent. Add in minced garlic and smoked sausage. Allow to cook for 1-2 minutes. Lower heat as needed to not burn garlic.
Add chicken broth to your pot and bring to a boil. Once your broth is at a boil add in red pepper flakes and green beans.
Reduce heat and cover. Allow to simmer for 60-90 minutes.
Season with salt and pepper to taste then serve.
Notes
Tip: After an hour check your green beans every 5-7 minutes to make sure they are tender, but not mushy.