Preheat your oven to 375 degrees F (190 degrees C). Place a small oven rack in the center of the oven.

Set a clear oven-safe glass baking dish (about 8×8 inches) on the counter. Open both cans of tuna, but do not drain them.

Carefully slide or tap the tuna out of each can into the baking dish, keeping the tuna in its whole cylindrical shape as much as possible, allowing the extra liquid to pour into the dish.

Use a spoon to gently nudge the tuna cylinders so they sit side by side in the middle of the dish.

In a small bowl, stir together the mayonnaise, yellow mustard, garlic powder, and dried Italian seasoning until smooth and creamy.

Spoon the seasoned mayo mixture evenly over the tops and sides of the tuna cylinders.

Place the glass baking dish in the preheated oven and bake for 18 to 22 minutes, until the tuna is heated through and the edges are lightly golden.

Carefully remove the dish from the oven and let the tuna rest for 3 to 5 minutes.

Serve the whole tuna cylinders as-is, spooning some of the seasoned juices over the top.

Alternatively, you can break them apart at the table and mix with the juices for a shredded, saucy tuna.