Leave 100g butter in a pan and sauté onions + garlic in it. Sprinkle in the paprika powder and sweat.
Score the tomatoes crosswise on the round side, scald in boiling water, rinse in cold water and cut into small pieces. Add to the onion and garlic mixture together with the potatoes. Season heartily with salt and pepper.
Preheat the oven to 175 ° C.
Pour the potato mixture into the mold, smooth it out and pour in the broth. Scatter thyme on top, place bay leaves on top. Spread the remaining butter on top in flakes. Cook the gratin in the oven preheated to 175 ° C for about 1 hour until all the liquid has been absorbed. Remove the bay leaves and serve the gratin.