Home » Food Sauce » How to Thicken Spaghetti Sauce: 10 Common Methods

How to Thicken Spaghetti Sauce: 10 Common Methods

Maria Foster
Last Updated on
by Maria Foster

What is the world’s favorite pasta shape? Spaghetti — and the sauce that comes with it!

A rich sauce is everything when you’re eating pasta, but we all have made watery spaghetti sauce at least once. It can be a nightmare to get the consistency right, but luckily, it’s an easy fix.

So, how do you thicken spaghetti sauce and save it from becoming a watery mess? There are ten methods, ranging from adding mashed vegetables, egg yolks, or cornstarch to simmering the sauce and using pasta water.

The most common ways to make spaghetti sauce thicker:

  • Simmer the Spaghetti Sauce
  • Add Mashed Potatoes
  • Boil the Pasta With the Sauce
  • Add Roux
  • Add Cornstarch
  • Use Pasta Water
  • Add Egg Yolks
  • Add Cheese
  • Add Arrowroot Powder
  • Add Tomato Ketchup or Paste
Spaghetti Sauce
Spaghetti Sauce

1. Simmer the Spaghetti Sauce

You can easily thicken a sauce by reducing its liquid contents. And how do you do that? By letting the liquid simmer and then evaporate. This approach will take around 30 minutes and will not impact the flavor of your sauce.

Simmer the Spaghetti Sauce
Simmer the Spaghetti Sauce

Start by bringing the sauce to a boil, then lower the heat. Frequently whisk your sauce to prevent overcooking. Use a shallow pan or a big pot, and don’t cover it while it simmers.

2. Add Mashed Potatoes

Mashed potatoes can be used as a thickening agent since they contain starch. Plus, the spaghetti sauce tastes better with them. (Tip: they are a fantastic way to balance flavors if your sauce is overly salty).

Add Mashed Potatoes
Add Mashed Potatoes

Start by peeling and boiling a potato using a julienne peeleer. Then, mash it to a purée and whisk well while adding cream or butter. Finally, add it to the sauce and stir vigorously. You don’t need to reheat the sauce before combining it with the mashed potatoes.

3. Boil the Pasta With the Sauce

You can also cook the spaghetti in the sauce. The sauce absorbs the starch from the pasta and thickens without changing flavors. It also allows the pasta to absorb the sauce better.

Boil the Pasta With the Sauce
Boil the Pasta With the Sauce

Start cooking pasta as you usually do, but drain the water before it is al dente. Combine the sauce and pasta in a pan and cook on low heat. Stir the pasta to release the starch. It will absorb the excess moisture and thicken the sauce.

4. Add Roux

Roux is a thickening agent for sauces and soups. It adds a subtle creaminess and a nutty taste to many dishes.

Add Roux
Add Roux

You can make a roux by combining equal parts flour and fat — commonly butter, although oil also works. Melt the butter on a skillet, add flour and stir for a couple of minutes over medium heat. Once it’s ready, add it to the spaghetti sauce.

5. Add Cornstarch

If you make a sauce that’s too thin, thicken it with cornstarch. Cornstarch has the benefit of not having a distinct flavor, so it won’t interfere with the taste of the sauce.

Add Cornstarch

To make a creamier sauce, combine equal parts cornstarch and water — no oil necessary. Stir carefully to avoid clumping before adding the mixture to your sauce.

To prevent the sauce from becoming too thick, gradually add the mixture and whisk for a few minutes on low heat to observe the results. If it’s still too thin, add a little more until it reaches the perfect consistency.

6. Use Pasta Water

When making homemade spaghetti sauce, use pasta broth to simmer instead of ordinary water. Why? Because the pasta water contains a lot of starch, a potent thickening agent.

Use Pasta Water
Pasta Water

Add ¼ or ½ cup of pasta water to your sauce and let it simmer on medium heat. You’ll see the sauce thicken in a minute or two. For this to work, your pasta broth must be from classic wheat pasta. Gluten-free pasta does not contain starch and can’t thicken the sauce.

Also, remember that this method only works if you make the sauce from scratch. Adding broth to an already thin sauce makes it even more watery.

7. Add Egg Yolks

Are you a carbonara fan? Egg yolk is a fantastic ingredient that can thicken and flavor your sauce.

Add Egg Yolks
Add Egg Yolks

However, if you just drop the egg into the sauce, it can cook quickly and become scrambled eggs. Instead, put it in a mixing bowl with a few tablespoons of the sauce, and mix well. Then slowly pour the mixture back into the sauce. Stir gently over low heat to ensure the sauce retains the right consistency.

8. Add Cheese

A particularly effective way to thicken spaghetti sauce is with cheese. You can add any melting cheese to your sauce — parmesan, cheddar, cream cheese, mozzarella — you name it.

Add Cheese
Add Cheese

You can even mix a few different types of cheese to get a creamier texture and a richer flavor. Simply grate the cheese and bring the sauce to a boil.

Then, gradually add the cheese to the pan over low heat, and keep stirring. Finally, add the spaghetti, stir for a few minutes, and then serve once everything is thoroughly blended.

9. Add Arrowroot Powder

Are you looking for a vegan way to thicken your spaghetti sauce? Try arrowroot powder. Since arrowroot lacks a distinctive scent or flavor, it’s an excellent way to thicken spaghetti sauce without affecting its taste.

Add Arrowroot Powder
Add Arrowroot Powder

To start, make a thick paste by combining arrowroot powder and water in equal parts. Next, bring your sauce to a simmer over low heat.

Don’t bring it to a boil, as adding arrowroot paste to the boiling sauce can mess up the texture of the sauce. Just let it simmer until it warms up.

Once it’s warm, slowly add the arrowroot mixture and stir along the way.

10. Add Tomato Ketchup or Paste

You can also reduce the amount of liquid in the sauce by adding more solids, such as ketchup.

Add Tomato Ketchup or Paste
Add Tomato Ketchup or Paste

If you don’t have ketchup, tomato paste will do just fine. To avoid a ketchup-heavy spaghetti sauce, gradually add ketchup or tomato paste to the sauce. Let everything simmer over low heat for a couple of minutes and enjoy.

How to Avoid Watery Spaghetti Sauce?

The trick to making a rich spaghetti sauce is to let the water drain or evaporate during the cooking process. Here are some tips to help you avoid a watery sauce.

Wait for the Spaghetti to Fully Drain

If the pasta isn’t properly drained, you’ll probably have a watery spaghetti sauce. Vapor from the boiled pasta can turn into a pool of water when you combine it with the sauce.

So drain properly, and wait a bit until the pasta cools down. Don’t rinse the pasta, as that can also add water to the sauce.

Wait for the Tomatoes to Fully Drain

The sauce can be too thin if your tomatoes aren’t fully cooked. Simmer the tomatoes for about 45 minutes to get a delicious, thick sauce.


Hopefully, our tips will help you prepare thick and flavorful spaghetti sauces. We listed all the thickening agents that will get your spaghetti hot under the colander, so pick one and enjoy.

You can add cornstarch, egg yolks, spaghetti water, cheese, arrowroot powder, mashed potatoes, and many other ingredients to improve the consistency of your sauce.

Simmering the tomatoes properly for about 45 minutes and draining the pasta before combining it with the sauce will help you make a great sauce every time.

About Maria Foster
Maria Foster
Maria Foster is a mother of 3 and she and her husband of 23 years share their home with 2 faithful dogs. Besides being CEO of the household and active in her community, Maria is the lead contributor to Food Champs and loves to try new food ideas and kitchen accessories to make easier and more delicious meals.
Maria Foster
Leave a Reply

Your email address will not be published. Required fields are marked *