Source.

Ingredients

• 1 28 oz can whole tomatoes
• 4 tbsp butter
• 1 onion

Instructions

1. Blend the tomatoes briefly with an immersion blender.
2. Combine the tomatoes, butter and onion over medium heat. When the mixture comes to a boil, turn down to low.
3. Simmer for 45 minutes. Discard the onion before storing