Poppyseed Stollen (Mohn Stollen)

Instructions

• First, make the fondant. It needs to be refrigerated overnight before using. To make the fondant, you'll need a marble slab or a baking sheet and an offset spatula to fold the candy. If you're using a baking sheet, rinse it with water, leaving a few drops on the pan.
• Dissolve the cream of tarter in the water in a heavy-bottomed saucepan. Add the sugar and bring the mixture to a boil over medium-high heat. Swirl the pan occasionally to help dissolve the sugar. Do not stir once the sugar syrup begins to boil. Heat to 240 degrees F (115 degrees C), or until a small amount of syrup dropped into cold water forms a soft ball that flattens when removed from the water and placed on a flat surface.
• Immediately pour the candy onto the baking sheet or marble slab and let cool for 10 minutes. Use a spatula to vigorously knead the candy, folding it over itself. Knead until it begins to look cloudy, 5 to 10 minutes; allow it to cool. Transfer the fondant to a heatproof bowl or the top of a double boiler. Refrigerate overnight.
• To make the sponge, dissolve the yeast and 1 teaspoon sugar in 1/4 cup of the room-temperature milk. Pour the remaining 1/2 cup milk into the bowl of a stand mixer. Add 1 cup of flour and the yeast mixture. Mix with a fork to combine. Cover the bowl with a towel and allow to rest until bubbly, 10 to 15 minutes.
• Stir the remaining 3 cups of flour, 1/4 cup sugar, salt, room-temperature eggs, and zest from 1 lemon into the sponge. Use the dough hook to mix the dough on the lowest setting. Mix the dough for about 5 minutes, occasionally scraping the dough off of the hook and down the sides of the bowl.
• Increase the speed to medium-low and add the softened butter 1 tablespoon at a time until fully incorporated. Allow the dough to mix for an additional 5 minutes, scraping the dough down as needed. Add the ground almonds and turn the mixer on for 1 or 2 turns, mixing just until incorporated. Transfer the dough to a lightly floured work surface and shape it into a ball. Place the ball in an oiled mixing bowl and cover with plastic wrap and a kitchen towel and let it rise until doubled, 1 1/2 to 2 hours.
• While the dough is rising, prepare the filling. Heat the milk in a heavy 4-quart saucepan until it begins to boil; stir in the butter and sugar. Remove the pan from the heat and add the poppyseeds, 1 1/2 teaspoons of lemon zest, and the cinnamon. Let the mixture stand for 30 minutes to soften the poppyseeds. When the mixture is cool, whisk in the egg.
• Punch down the dough and roll it out into a 10 1/2- by 16-inch rectangle. Spread the filling evenly over the dough, leaving a 1-inch margin on all sides. Roll the dough up into a log, starting with the long side, and pinch the edges together to form a seam. Place the loaf, seam-side down, on a parchment-lined baking sheet. Cover it with greased plastic wrap or a well-floured kitchen towel and allow it to rise for an additional 30 to 40 minutes.
• Preheat an oven to 400 degrees F (200 degrees C).
• Bake the stollen until golden brown on the bottom of the loaf, about 40 minutes. Let the bread cool completely before glazing.
• To glaze the bread, add the lemon juice to the fondant. Place the bowl over a pan of simmering water, stirring frequently with a rubber spatula until soft and glossy. Pour the fondant over the stollen and allow it to cool before slicing.