Melt butter in a skillet and add in onion, garlic, carrot  and celery slices and cook on low heat

Cook until onions are transparent but not brown

Pour broth into a stockpot and add in contents of the skillet, stir to combine 

Add in broccoli florets and cook on medium heat for 30-45 minutes

Turn off the soup and allow to cool

When cooled down, pour soup in batches into the blender and pulse until broccoli is almost completely liquefied

Return the soup to the stock pot  and add in sour cream and cheddar cheese, stir

Cook for 20-30 minutes, stirring often (for a thicker soup add in a roux made of half and half cream and flour)

Serve with Garlic Parmesan Crackers  

Garlic Parmesan Crackers:  Cut shapes from 2 flour tortillas, add to baking tray, drizzle olive oil and sprinkle garlic powder over the cutouts and bake at 350 degrees Fahrenheit until tortillas puff up and brown at edges, flip once to brown on both sides, serve with soup