Melt 1 tablespoon of the butter in a skillet over medium high heat.
Dice the onion, add it to the melted butter, and saute for 3 minutes.
While the onion is cooking mince the garlic.
Add the garlic to the pan and saute for and additional 2 minutes.
Add the remaining butter and melt.
Add cassava flour and whisk to combine.
Saute 2-3 minutes until a thick roux forms.
Gradually, whisk the chicken broth into the mixture until all is added.
Add the broccoli, carrots, and celery and simmer for 20 minutes or vegetables are softened.
Stir in the milk and shredded cheese and heat over medium low heat until just melted.
Season with salt and pepper to taste and serve
You can use fresh or frozen broccoli, just make sure it’s chopped into bite-size pieces. Fresh broccoli may need a few minutes longer to cook.
I find that the easiest way to shred carrots is in a food processor. This makes perfect matchstick size shreds for soup. If you do a large quantity at once, you can freeze them and then just cut off and thaw as much as you need.