Put the potatoes in a large saucepan. Cover with cold, salted water and bring to a simmer over medium heat. Cook for 15-20 minutes until soft. Drain and leave to cool slightly.
Cut the red cherry tomatoes in half.
Pre-heat the oven to 180°C.
Grease a muffin tin with olive oil. Place the potatoes in the muffin holes (one in each hole). Season the potatoes with extra olive oil, salt, and pepper. Use a glass/back of a spoon to press/crush the potato into the muffin tin to form an indentation and a rim.
Top the potato in the cavity with the tomato sauce, cherry tomatoes, crème fraiche and grated mozzarella cheese.
Bake the muffins for 20-25 minutes until golden brown.