Stir brown sugar, garlic, butter, Worcestershire sauce, and cayenne in a large bowl and mix until combined. Season with desired amounts of salt and pepper.
In a large skillet over med-high heat, saute onions in bacon grease until softened and somewhat see through. Season with red pepper flakes and desired amounts of salt and pepper, then remove from heat.
Lightly grease slow cooker and place green beans and onions into it.
Pour garlic butter mixture over them. Stir until well incorporated and top with tons of crumbled bacon.
Cover and cook on low for 4-5 hours. Serve hot.
ENJOY!
