In a large pot, melt the butter over medium heat. Add the chopped onion and sauté for about 5 minutes until softened.
Stir in the minced garlic and cook for an additional 1 minute until fragrant.
Add the diced potatoes, broth, corn, thyme, salt, and pepper to the pot. Bring the mixture to a boil.
Once boiling, reduce the heat to low and cover the pot. Let it simmer for about 20 minutes or until the potatoes are tender.
Once the potatoes are cooked, use a potato masher or fork to mash a portion of the chowder to achieve a creamy consistency, leaving some chunks for texture.
Stir in the heavy cream and heat through for another 2-3 minutes.
Taste and adjust seasoning if necessary.
Serve hot, garnished with fresh parsley.