Bake the french fries in the oven for up to 3/4 of the specified time according to the instructions on the packet. Take out the tray.
Cut the tomatoes into slices and distribute evenly on the fries, season with salt and pepper. Spread the basil leaves on the tomatoes. Cut the mozzarella into slices and pour over the tomatoes. Put the tray back in the oven and bake until the cheese runs and browns a bit.