Heat the oil in a pot and add the onions and garlic. Cook slowly until translucent (do not burn). Once the onions are translucent, add the chicken broth.

Bring the broth to a boil and add the potatoes. Once the broth begins to boil after passing the potatoes, reduce the heat to medium. Cook the potatoes several minutes until the potatoes soften.

Add the light cream, corn, rosemary, salt, pepper, and butter.

Let the chowder cook for a few minutes. Slowly add cornstarch to thicken the chowder until you reach the desired consistency (I add a teaspoon at a time and let the chowder simmer for a minute or so between each teaspoon to allow it to thicken).

Once the chowder reaches the desired consistency and you've reached the desired taste with the spices, you may remove from the stove. I try not to cook it too long after adding the cream, etc. because I don't like when the potatoes begin to fall apart.