Slice the kernels from both ears of corn. Bring water, kosher salt and leftover corn cobs to a boil, covered. You may need to break the cobs in half. Boil for the duration of the next steps, or at least 20 minutes.
Dice onion. Cut carrot into thin discs. Cut zucchini into half medallions.
Melt butter or ghee in a large pan over medium heat. Add onions and cook, stirring occasionally, until they start to become translucent - about 15 minutes.
Add carrots and corn to onions. Cover and cook for 10 or so minutes, stirring occasionally. You want to have vegetables that are cooked through, but still retain some of their crunch and texture.
Add half of your onion / carrot/ corn mixture to the boiling water, reserving the other half in the pan. Boil, covered, for about 5 minutes or until the veggies are totally soft.
In the meantime, add the zucchini to the remaining vegetables in the pan. Cover and cook until the zucchini is soft but not mushy. Remove from heat.
Turn the heat off on the boiling water once the vegetables you added have cooked through. Fish out the corn cobs with a slotted spoon and discard.
Add heavy whipping cream, garlic powder, onion powder and pepper to the pot. If you have an immersion blender, use that to blend the soup until thickened and no large chunks remain. If you are using a regular blender, pour the soup mixture into that and let cool slightly. Blend until thickened with no large chunks remaining. Return to pot.
Add the remaining vegetables from the frying pan and heat through. Garnish with green onions, cilantro or parsley if desired.