In a medium pan, melt 1 ½ tbsp of butter on medium heat. Add onions and cook until soft and turn golden brown. Set aside. In a large pan, heat sour cream on low. Season with salt and pepper. Do not boil to prevent curdling/separation. Fold in the sour cream and caramelized onions. Season with salt & pepper. Cook ravioli according to packaging instructions. Strain and toss ravioli in the pan with the sauce. Sprinkle with chives and serve.