Meanwhile, heat a large frying pan on medium-high. Drain oil from one of the cans of Sealord tuna chunky style in oil into the pan (discard oil from the other can). Sauté onion and garlic until soft (about 3 minutes). Stir in tuna, then add tomatoes and stock powder. Bring to a simmer. Stir in cream cheese and half of the parmesan.