Mussels and spinach in tomato broth

Ingredients

• 1 Package of frozen mussels (use fresh if available)
• 1 package fresh spinash (about 3-4 cups if buying in bulk)
• 1 can tomato sauce
• 2 tbsp tomato paste
• 2 cloves of garlic
• 1 1/2 tbsp herbs de Provence
• 1 tsbp gray salt
• 1 tbsp butter