1. Sift the flour into a large bowl. Add the salt and cold butter and cut the butter with a pastry blender* into pea-sized pieces. Add the egg and one tablespoon of the ice water. Use your hands to form a nice ball of dough. Add some more water if the crumbs are not coming together. Wrap the dough in plastic wrap and place it in the fridge for about 30 minutes.

2. Clean and wash the Swiss chard and let it drain. Cut off the thicker stems, but leave 2-3 small leaves untouched for the decorations – set those aside. Cut the stems and leaves separately into strips. Next, cut the shallots into thin slices.

3. Add the olive oil to a large pan or wok and heat up. Add the shallots and cook them until soft and glossy. Next, add the Swiss chard stems and bacon (optional) and cook/fry for about 4-5 minutes. Add the remaining cut leaves and let them cook only for a short time. They should lose some volume, but not get mushy. Season with salt and pepper and remove from the heat.

4. Mix sour cream, heavy cream, and eggs in a small bowl. Add the grated cheese and diced mozzarella and mix in. Season well with salt and pepper and set aside.

5. Preheat the oven to 220°C (425°F). Grease a 26cm (10 inches) tart tin with loose bottom* Take the dough out of the fridge and roll it out on a floured surface. Place it in the baking tin and press to the bottom and sides to create a nice crust. Prick the bottom several times with a fork. Line with baking parchment, place some baking beans* on top and blind bake the crust for about 15 minutes. Take it out of the oven, remove the baking parchment and baking beans and reduce the heat of the oven to 180°C (350˚F). Add the Swiss chard to the pre-baked crust, pour the sour cream mixture on top and decorate with the cherry tomatoes and the Swiss chard leaves you kept on the side. Bake the tart for about 30-35 minutes. Take it out of the oven and let it cool down for about 10 minutes, then serve with a salad, for example.