In a large saucepan, add the chicken broth, kosher salt, black pepper, onion powder, garlic powder, and thyme. Whisk to combine.
Add the broccoli. Bring to a boil over high heat. This should take about 5 minutes if using fresh broccoli and 10 minutes if using frozen. Reduce the heat to medium, cover, and cook until the broccoli is very tender, 10-15 minutes.
Turn the heat off. Using an immersion blender, blend the soup until smooth.
Turn the heat up to medium-low. Stir in the heavy cream and parmesan. Cook the soup just until heated through, about 2 minutes. Don't let it boil. Serve immediately.
Video
Notes
Salting the Soup
How much salt you should use depends on how salty your chicken broth is. So, it's a good idea to taste the soup after you mix in the heavy cream and Parmesan to make sure it's salty enough to your taste.
Blending the Soup
There are two ways to puree a soup. For a very creamy texture, working in at least two batches, carefully transfer the hot soup to your stand blender. Blend each batch until completely smooth and transfer it to a bowl. When all batches are done, return the pureed soup to the pot and proceed with the recipe. You can see the results of this method in the photos on this page - very smooth and creamy.The second method is to use an immersion blender and blend the soup right inside the pot. I used this method when filming the video, and as you can see, the soup is not as creamy. However, it's just as tasty, and using an immersion blender is easier.Which of these methods you choose is up to you. Both work and both yield great results, just different textures.When using a stand blender, never fill your blender past the maximum fill line. It's best to fill it no more than half full. If the lid of your blender wasn't designed to allow steam to escape, remove the centerpiece and drape a clean towel on top of the lid. You can hold down the lid when blending to prevent it from being pushed off, but do so without placing your hand or face over the hot steam.
Storing Leftovers
You can keep the leftovers in an airtight container in the fridge for 3-4 days. Gently reheat them on the stovetop over low heat or in the microwave, covered, at 50% power. Don't allow the soup to boil when you reheat it.You can also freeze this soup. I like to freeze individual portions of this soup in covered mugs or mason jars. To prevent the frozen soup from curdling when reheated, I reheat it covered in a 50% power microwave in 30-second sessions, stirring often.