Slow Cooker Tomato Sauce

There are very few smells that make me feel nostalgic quite like a Sunday sauce. Regardless of what you call it in your home (whether it be gravy, red sauce, marinara, or spaghetti sauce) if you are an Italian-American, like me, you likely grew up with something like this simmering away on a Sunday morning.

My own version of tomato sauce is made in the slow cooker, and is very different from the one I grew up with. It is infinitely inspired by Marcella Hazan's famous tomato sauce. I first learned of that simple yet profound butter-and-onion tomato sauce more than a decade ago, and this recipe is my take on it. Over the years, I’ve tweaked it to fit my own preferences, adding a few more herbs and spices along with a small pinch of sugar. I did not originally make it in the slow cooker, but the busyness of motherhood necessitated it, and I am glad it did. Letting it simmer all day slowly deepens the flavor in a way that feels truly special.

And, it can be made overnight! It comes together very quickly, and then you wake up to the most beautiful aroma, and you have the perfect tomato sauce: well-balanced, super flavorful, and incredibly smooth-tasting, with little acidity.

How to Make It

Using the slow cooker is not only convenient for dinner, it is also key to the flavor of this tomato sauce. The gentle, low-and-slow simmer with butter and onion softens the acidity while bringing out a deeper tomato flavor.

One small note on slow cooker lids and evaporation: Some have locking lids that create a very tight seal, which is not ideal here. This sauce benefits from a bit of natural evaporation as it cooks, so if your lid has locks, leave them undone while the sauce simmers.

This recipe calls for San Marzano tomatoes. This is simply because I believe they lend the best flavor to this recipe. They are worth the effort to seek out and buy for this recipe, most grocery stores carry them. Can you make this recipe without canned San Marzano? Sure, it just won't be as good.

Storing It

I always like to keep extra tomato sauce in the freezer for quick, easy dinners. This sauce stores well in both the refrigerator and the freezer. Keep it refrigerated for 3 to 4 days, or freeze it for up to 3 months.

If freezing, leave some space between the sauce and the container lid, especially if using glass, since the sauce will expand as it freezes and could cause the container to crack. To avoid this, let the sauce cool completely in the refrigerator overnight before transferring it to the freezer. When reheating from frozen, thaw it in the refrigerator for 12 to 24 hours, if possible, or warm it in the microwave, or set the container in a bowl of hot water until the sauce loosens around the edges, then remove and use as desired.