On a large sheet pan prepared with a silicone mat, parchment or greased foil, add the cubed sweet potatoes and the onions. Drizzle the oil over the vegetables. Season with a grinding of fresh sea salt and ground black pepper. Rub the seasonings and oil into the vegetables and spread out. Add the garlic and thyme sprigs alongside the vegetables at this point.
Roast for 25 to 30 minutes, turning halfway, until veggies are roasted and sweet potatoes are cooked through.
Remove from oven and remove the skins from the garlic.
In a large blender, add all the remaining ingredients with the vegetables (if your thyme isn't dried out, you can pick the leaves off the stems and add that in too). Ensure that the broth is very hot. If you're not using large blender (holds at least 6 cups) then do this in increments.
Using the soup setting on your blender, or a very powerful blend option, blend until creamy and smooth. My blender automatically blends for about 3 minutes continuously.
Taste and add salt and pepper to taste if necessary.
Top with garnish (I used some thyme leaves that I removed from their stems and some extra cinnamon).
Serve into bowls and enjoy!
NotesThe broth needs to be very hot so that if helps to break down the vegetables, and so that you can serve the soup right out of the blender. You can do this by heating it in the microwave or even on a stovetop if you’d like. I had just made very fresh boiling hot broth and used that.