Peel and wash the potatoes. Cook in boiling salted water for about 20 minutes, drain and immediately mash or press through a potato press. Let the potatoes cool down a little
Warm the milk in a small pot and melt butter in it. Mix flour and yeast in a bowl. Add the milk, butter and potatoes and knead everything with the dough hooks of the hand mixer briefly at the lowest setting, then at the highest setting for about 5 minutes to a smooth dough. Knead ham nuggets briefly. Cover the dough and let it rise in a warm place until it has visibly enlarged
Grease a springform pan (18 cm Ø with tube sheet insert) and sprinkle with sesame seeds. Peel the onion. Clean the mushrooms and clean them. Peel and quarter the pear and cut out the core. Dice everything finely. Heat the oil in a pan and fry the onion cubes until transparent. Add mushroom and pear cubes and steam for about 5 minutes. Mix crème légère and starch and stir in. Season to taste with salt and pepper. Dice blue cheese
Knead the dough once again briefly, form into a roll and roll out into a rectangle (approx. 30 x 35 cm). Spread the filling evenly on top, leaving approx. 1 cm free at the top long edge. Spread cheese cubes on top. Roll up the dough from the long side and place it in the mould, pressing the ends together. Let the wreath rise for about 20 minutes
Bake on a grid covered with baking paper in the lower third of the preheated oven (electric oven: 200 °C/ convection oven: 175 °C/ gas: level 3) for approx. 40 minutes. Let the cake rest in the form for approx. 10 minutes, turn out onto a cake rack and serve warm
Waiting time approx. 1 hour