My family loves this recipe. I cook it in the instant pot, first sautéing the onions in a spot of olive oil, then I add 1 cup of the chicken stock along with chopped broccoli and carrots. Pressure cook for 3 min. I made the roux with the remaining stock, butter, flour, spices and milk on the stove and dumped it in the instant pot when it was done, added cheese and stirred it all together. You could use an immersion blender to smooth it out. I added a bit of extra stock as well.
