Make a dough out of the flour, water and margarine. Wrap the dough in foil and place in the refrigerator for 1 hour.
In the meantime, peel the sweet potatoes and roots and cut into cubes or wheels. Then fry the bacon in a pan for 3 - 4 minutes (roasted aromas). Then add the sweet potato cubes and the carrots and sauté in the pan with the lid for 16-17 minutes with the bacon. Stir every 3 - 4 minutes. Then let it cool down.
Preheat the oven to 200 ° C top / bottom heat.
Take the dough out of the fridge and roll it out on baking paper. The dough should be rolled out so far that you can lift it with the parchment paper over the 26 or 28 springform pan and use it with feeling. This saves you from greasing the mold and makes it much easier to clean it later. The dough now covers the bottom of the pan and the edge.
Whisk the cream, milk and eggs with the whisk and add to the pan with the bacon, carrots and sweet potatoes. Put the mixture in the mold on top of the dough. Spread the sweet potatoes and carrots with the bacon a little. That looks fluid. Do not worry! That stagnates in the oven due to the eggs. Now, depending on your taste, add the freshly grated Parmesan on top of the filling.
Place in the hot oven for about 30 minutes (middle rack).
Then take it out and remove the ring from the springform pan. Pull down the parchment paper and cut pieces of cake with a sharp knife.