In a large skillet over medium heat, cook bacon until crisp, then Transfer cooked bacon to a paper-towel lined plate.
Drain most of the bacon grease from the skillet, leaving about 2 tbsp. left in the pan.
Add diced onions and saute until tender, about 3-4 minutes.
Combine tomato ketchup, Sweet Baby Ray's barbecue sauce, brown sugar, Worcestershire sauce, salt, pepper, and cayenne pepper in a medium bowl and whisk until smooth and well combined.
Spray the inside of a slow cooker with non-stick cooking spray and add green beans, sauteed onions, and barbecue sauce mixture.
Stir to combine and sprinkle top with cooked bacon. Cover and cook for 4-5 hours on LOW heat.
ENJOY!