You need 2 tomatoes, 4 eggs, 4 slices of mozarella (or other type of cheese that melts the same way) and basil leaves.
Half the tomatoes and remove the seeds and most of the flesh, creating a cup. Place in a tray lined with baking paper.
Place a small egg in every tomato half (you need small eggs, otherwise they wonțt fit and you have to separate and store separately a part of the egg white).
Bake in the pre-heated oven (200 C) for 15-20 minutes. When the egg is partially baked, cover each tomato half with a mozzarella slice.
Leave in the oven for another 15-20 minutes. The result will be a runny egg.
For the kids, it's recommended to bake the eggs until the yolk becomes completely solid. So, cut a little bit through the egg yolk using a sharp knive (or you can even cut the whole tomato and egg in half) and place back in the oven for another 10 minutes (the heat can be turned off, it will cook from the residual heat).