Bake broccoli florets seasoned with salt, pepper and butter for 10 minutes in a preheated oven.
Heat oil in a heavy bottomed pot and add the chopped onions and garlic and saute until softened.
Next, add the flour and cook for 1-2 minutes, stirring continuously. Now add the stock and heavy cream and let this mixture simmer for 2-3 minutes.
Add the broccoli florets, reserving a handful to add in towards the end. Let the broccoli cook for 5-7 minutes, remove from heat and blend everything using an immersion blender.
Bring the pot back to heat and add in the remaining broccoli, the seasonings and cheddar cheese and cook for 2-3 minutes before you serve.