I would like to know what to use and how much, in place of flour to thicken the sauce in the following recipe and make it keto.

This is the full recipe:

  • 2 Tbsp butter
  • 1 small yellow onion, diced
  • 4 large garlic cloves, minced
  • 1/2 cup chicken broth
  • 1/2 tsp garlic powder
  • 1/4 tsp pepper
  • 1/2 tsp salt
  • 8 oz sliced mushrooms (optional)
  • 1 1/2 lbs boneless skinless breasts sliced into 1/2 inch filets
  • 1 cup half and half
  • 2 Tbsp flour
  • 1/2 cup parmesan cheese
  • 3 oz coarsely chopped spinach
  • Salt and freshly ground pepper

Turn your Instant Pot to the saute setting (more). When the display reads HOT add in the butter. Once the butter is melted add in the onions and saute for about 3-4 minutes. Add in the garlic and saute for 30 seconds. Add in the chicken broth, garlic powder, pepper and salt. Stir. Add in the mushrooms (if using) and chicken. Cover the pot and secure the lid. Make sure valve is set to sealing. Set the manual/pressure cook button to 6 minutes (this is the cooking time for the 1/2 inch pieces of chicken breast, if they are thicker than that you may need more time). Let the pressure release naturally for 10 minutes and then move the valve to “venting.” Remove the lid. Use tongs to place the chicken on a platter. Loosely cover with foil. Turn the Instant Pot to the saute setting. Warm the half and half up in a pyrex measuring cup for 45 seconds in the microwave. Whisk the flour into the half and half until it’s smooth. Whisk the mixture into the Instant Pot. This will thicken up the sauce in a few minutes. Add in the parmesan cheese. Add in the spinach. Salt and pepper to taste. If using pasta, drain any water off of the pasta and stir into the pot.

  • 1
    Practically speaking, I would not recommend mixing flour (or other thickener) into warm milk or cream. The risk of lumps is far less with cold liquid.
    – Stephie
    Oct 29, 2020 at 13:46

3 Answers 3


One option is foregoing thickener entirely. I regularly make sauces with those proportions and no thickener and find them perfectly fine, texture wise.

Another option is substituting the half and half with full cream or even switch 1/3-1/2 of it for cream cheese. Or, similarly, add more parmesan or another cheese to thicken the sauce. All of those substitutes will make for a thicker sauce without any further additions.

Otherwise, xantham gum is keto friendly. You want to add about 0.2% xantham gum by weight to slightly thicken a sauce, so about 1.5 grams for your recipe (I recommend weighing your sauce on a kitchen scale and calculating the amount precisely). I would mix it well with a small amount of cream like for a cornstarch slurry, before mixing that into the rest of the liquid. Like Stephie pointed out in the comments, mixing any powder into a hot liquid is very difficult.


Egg yolk is a possible alternative. One or two per cup of liquid works for gravy, so I would suggest two to four in your recipe.

An out of fashion thickener is blood (totally keto!). It once was commonly used. You may be able to find it in an Asian market near you. I haven't tried it, so can't suggest an amount.

  • Blood is a good thickener, but probably not a good choice for this recipe - especially considering the expected color >.<
    – Stephie
    Oct 29, 2020 at 15:45

I'd recommend resistant wheat starch or resistant corn starch, if you're able to get your hands on them. They both look and function quite similar to regular starch. Resistant Wheat Starch 75 has about 1 g net carbs per 1 Tbsp (unfortunately, it looks like it's been out of stock for months). Resistant Corn Starch 260 has around 3 g of net carbs per 1 Tbsp.

I've successfully used resistant wheat starch to make a roux which I used to thicken a tomato soup. I used 2 Tbsp of RWS + 2 Tbsp of butter heated separately in a pan till it thickened, then added gradually to the soup base.

The result was amazing. The texture was right on: the soup resisted stirring, and the faster you stirred, the more it would resist. The mouthfeel was also close to the real thing as far as I can remember.

Alternatively, you might try making a roux out of fine psyllium husk powder and a fat or cream. I'd probably start at 1 Tbsp and adjust from there.

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