Place a large saucepan over a medium heat. Add oil then garlic, cook for 30 seconds – 1 minute, stirring to prevent the garlic burning. Add the butter and allow to melt then add in the onion, leek, fennel and broccoli stalk - cook until softened, about 10 -15 minutes until soft and translucent.
Add the potato and stock, bring to boil and reduce to simmer, cook for 15-20 minutes. Add the broccoli florets and milk, gently simmer for 8-10 minutes, until broccoli is tender. Add the herbs and season with salt and pepper
Transfer to liquidizer and blend to smooth in batches, fill a blender halfway with mixture and puree until smooth (use caution when blending hot liquids). Return pureed soup to pot and add the cream and 2/3 of the gorgonzola. Bring back to a low simmer allowing the cheese to melt into a velvety cream.
To serve: Ladle the soup into serving bowls and top with leftover gorgonzola.