In a small saucepan (a 1.5 quart pot works well) add a little olive oil and turn on to medium high heat
While the pot is heating, take ½ of the onion and chop it into small pieces then add it to the heated saucepan.
Cook the onions for about 2 minutes. While the onions are cooking, peel and mince the garlic.
Add the minced garlic to the onions in the saucepan and cook for another minute.
(Skip to this step if using powdered onion and garlic) Next add in ¾ cup of the broth, reserving ¼ cup, all the milk, and the seasonings.
Cook for about 7 minutes total so the flavors of the herbs and garlic and onion can infuse into the milk and broth. Let the mixture come to a boil then turn down to a simmer.
While the broth is cooking, create a slurry by mixing the cassava flour with the ¼ cup reserved broth. Use 1 tablespoon cassava flour for thin gravy and 2 tablespoons cassava flour for thick gravy.
Add the slurry to the gravy mixture after it has cooked for 7 minutes. Mix until well combined and let cook for another 1-2 minutes until the gravy has thickened. This yields about 1 ½ cups of gravy or 5 servings.
Serve immediately on mashed potatoes, meat, or veggies. To save for later, store in an airtight container in the refrigerator for up to a week or in the freezer for 4-6 months.