Using a sharp knife, carefully butterfly each salmon filet through the center. In a large bowl mix the next 8 ingredients (spinach through lemon juice). Divide filling and spread onto the butterflied salmon filets. Roll up each fillet and tie shut with cooking twine.
Grease a large skillet with the oil and heat to medium heat, placing the salmon inside. Pour the broth on top, cover and cook on medium to low heat for 10 to 15 minutes, occasionally spooning over the cooking liquid, or until salmon easily flakes with a fork.