Preheat the oven to 180°C (approximately 350°F). Trim and rinse the zucchini and cut into thin slices. Rinse the tomatoes. Brush 4 small ramekins with butter. Arrange the zucchini slices and cherry tomatoes in the ramekins.
Whisk together the cream, milk, eggs and cornstarch and season with salt and pepper. Pour the cream mixture over the vegetables and place in the preheated oven and bake for about 20 minutes. Serve hot.