Melt butter/ghee in a medium pot over medium-high heat.
Add garlic, onions, and celery, then sauté for 3-4 minutes until veggies begin to soften.
Add zucchini, potatoes, broth and bring to a boil. Once boiling, cover and reduce the heat to a low simmer.
Cook for 20 minutes or until veggies are fork tender. Taste and season with sea salt and fresh ground black pepper to your taste.
Using an emersion blender, blend until smooth and creamy, then stir in the plain Greek yogurt.
Serve hot, garnished with crumbled bacon and parmesan sprinkled on top if you like!