Wash the potatoes and cook in boiling salted water for about 20 minutes. Drain and let cool down a little. Peel and press them still warm through a potato press. Let the potato mixture cool down completely. Knead egg yolk, flour and semolina with the potato mixture until the dough is formable. Form small gnocchi from the dough, press them in slightly with a fork. Pour into boiling salted water.
Leave to stand for 4-6 minutes until they float to the surface. In the meantime, clean, wash and halve the tomatoes. Pluck off sage leaves.4 Brush the ramekins with olive oil. Add the gnocchi, tomatoes and sage leaves. Season with salt and pepper. Spread small flakes of fat on top. Grate the Parmesan and Gouda cheese and bake in a preheated oven (electric: 200 ° C / gas: level 3) for about 15 minutes and serve.