Preheat oven to 375°F (190°C). Place a small (8-10 inch) cast iron skillet in the oven while it heats.
In a small bowl, combine diced tomatoes, garlic, oregano, ají gustoso, 1 tablespoon olive oil, salt, and pepper. Stir and let sit 5 minutes.
Carefully remove hot skillet from oven. Drizzle remaining 1 tablespoon olive oil on the bottom. Place block of queso crema San Juan in the center.
Spoon tomato mixture evenly over the cheese, including all oil and herbs from the bowl.
Bake 18-22 minutes, until cheese is bubbling at edges and tomatoes have collapsed into a sauce.
Rest 3-5 minutes before serving. Serve hot from the skillet with plantain chips, almond flour crackers, or sliced toasted bread.