Bring water to a boil in a saucepan. Add oats, reduce heat to medium-low, and cook until tender, 10 to 15 minutes, adding more water if oats get too dry.
Combine oatmeal, tomatoes, basil, salt, and pepper together in a bowl. Beat eggs and cream together in a separate bowl. Fold egg mixture into oatmeal mixture; divide between 2 large ramekins or baking dishes. Top oatmeal mixture with feta cheese.
Bake in the preheated oven until cooked through, about 30 minutes.