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+ servings
a white bowl with ravioli and tomato sauce and a white fork.

Easy Tomato Sauce with Butter and Onion

A three ingredient tomato sauce that works beautifully with your favorite pasta or flatbread
Course Main Course, Pasta
Cuisine Italian
Prep Time 5 minutes
Cook Time 45 minutes
Total Time 50 minutes
Servings 4


  • 1 28 oz can whole, peeled Italian tomatoes preferably San Marzano
  • 1 yellow onion cut in half from root to stem, ends trimmed
  • 5 tbsp unsalted butter
  • salt and pepper to taste


  • In a blender or with a stick blender, blend tomatoes to desired consistency. I prefer my sauce smoother. You certainly can leave them whole and crush them right in the pan with the back of a wooden spoon.
  • Peel onion, cut in half, trim shaggy roots and add to the pan.
  • Add the butter a little salt and pepper (about 1 tsp of salt and maybe ½ tsp of pepper to start).
  • Simmer for 45 minutes uncovered until the fat starts to separate from the tomatoes.
  • Adjust seasonings with salt and pepper.


Options: If desired, add crushed red pepper or fresh basil but keep it simple. This is a delicate sauce and barely needs parmesan (but I usually add it).
Make ahead: Make this sauce a day or two ahead of when you plan to serve it. It'll keep in the fridge for up to 4 days.
Freezing Tips: Allow the sauce to completely cool before storing in a freezer safe container or ziploc bag. Can freeze for up to 3 months. Defrost in the fridge or microwave before heating.