In a large stockpot, add the butter and the onion. Saute over medium-high heat for about 3 minutes, until the onion begins to soften. Add the minced garlic and continue to saute until the onions start to become translucent—about 5-7 more minutes.
Add the broccoli, broth, salt, and pepper, and bring to a simmer. Continue to simmer uncovered for about 20 minutes, or until the broccoli is tender.
Once the broccoli is tender, turn off the heat. Carefully transfer the soup to a blender in batches (don't fill more than halfway), and blend until creamy.
Once all of the soup has been blended and well mixed, add it back into the stockpot and stir in the cream with a rubber spatula. Return to medium heat.
Meanwhile, in a small bowl, add the cold water and cornstarch and mix until well combined.
Slowly pour this cornstarch mixture into the soup while whisking. Continue to stir and cook for another 2-3 minutes, or until the soup is thickened.
Remove from heat and let cool slightly before serving before ladling into bowls, and top with shredded cheddar cheese, bacon bits and freshly chopped parsley. Enjoy!