Mushroom Strudel

In a small bowl, stir together the milk, yeast, and sugar and let stand for 10 minutes. In the bowl of a stand mixer fitted with the dough hook, combine the flour, salt, and butter. Add the whole egg, egg yolk, and milk mixture. Mix on low speed until a soft dough forms. Transfer the dough to a lightly floured work surface and roll it into a large ball. Cover the dough with plastic wrap and refrigerate for 30 minutes.

In a large sauté pan, cook the mushrooms over medium heat, stirring occasionally, until they turn brown and have released most of their moisture and the bottom of the pan is dry, 15 to 20 minutes. Stir in the oil, onion, salt, and pepper and cook until the onion is soft and translucent, 5 to 7 minutes. Add the speck and stir to combine. Remove from the heat and stir in the mascarpone until it melts and coats the mushrooms. Set aside to cool while you ready the dough.

Preheat the oven to 375°F.