Melt the butter in a large soup pot over medium-high heat. Add the onion and garlic and cook, stirring occasionally for 4-5 minutes until onion is soft.
Add the cubed potatoes, corn, ham, seasonings, and broth to the pot and stir to combine. Reduce the heat to medium-low and simmer for 10-15 minutes just until potatoes are fork tender.
Once the potatoes are tender, whisk the sour cream into the soup.
Measure the cream in a liquid measuring up and stir in the cornstarch until no lumps remain. Pour the cream mixture into the soup while stirring constantly.
Simmer the soup for 3-5 more minutes until thickened. Serve immediately garnished with shredded cheese, green onions, parsley, or extra sour cream if desired.
INSTANT POT METHOD:
Turn the instant pot to saute mode and add the butter. Once the butter is melted add the onion and garlic.
Cook the onion and garlic, stirring constantly for about 3-4 minutes until the onion is soft.
Turn the instant pot off. Add the cubed potatoes, corn, ham, all of the seasonings and the broth to the pot. Stir once to combine.
Place the lid on the pot and set the valve to sealing position. Cook the soup on manual/high for 8 minutes.
Once the 8 minutes is up, allow the pot to natural pressure release (don't do anything) for 10 minutes. Then, quick release the remaining pressure.
Carefully open the instant pot and stir in the sour cream. Whisk together the cream and cornstarch.
Turn the instant pot to saute mode. Stir the cream/cornstarch mixture into the chowder and allow to simmer for 3-5 minutes until thickened.
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Notes
NOTE: You can use fresh, frozen, or canned corn for this recipe. If using fresh, you will need about 4-5 ears of corn.NOTE: The bacon or ham in this recipe is optional if you prefer a vegetarian soup. Simply leave it out without any other changes.