Stollen

Combine all of the ingredients in a quart jar and seal the jar.

Let it sit at room temperature overnight or up to 3 days, turning the jar occasionally. Alternatively, place the ingredients in a small saucepan over low heat. Warm the mixture, stirring occasionally, just until steam starts to rise from the pan.

Heat the milk in a small saucepan over medium heat until it registers between 120°F and 130°F on an instant-read thermometer.

Remove from the heat.

Place the flour, sugar, and yeast in the bowl of a stand mixer and whisk by hand to combine.

Add the milk and whisk until smooth.

Add the egg and whisk until evenly combined.Cover the bowl tightly with plastic wrap.

Remove the plastic wrap from the sponge, attach the bowl to the mixer, and fit the mixer with a paddle attachment. Turn the mixer to medium speed and add the butter 1 piece at a time, letting each piece incorporate before adding the next, about 5 minutes total.Reduce the speed to medium low, add the sugar, cardamom, salt, almond extract, nutmeg, and vanilla seeds, and mix until the dough starts to collect in 1 mass on the paddle, about 10 minutes. Stop the mixer and, using a rubber spatula or rubber bowl scraper, scrape down the sides of the bowl and the paddle.

Remove the paddle and attach the dough hook.

Add the reserved fruit mixture (including any unabsorbed liquid) and almonds and mix on low speed until incorporated, about 2 minutes. Gradually add 2 cups of the flour, 1/4 cup at a time, about 5 minutes total. Once all of the flour has been added, continue to mix until the dough is starting to pull away from the bowl, about 3 to 5 minutes more.

Sprinkle a work surface with 1/2 cup of the flour and scrape the dough out onto it. Knead the dough, pushing any fruit or nut pieces back in that fall out, until all of the flour is incorporated and the dough feels slightly tacky and fairly firm, about 7 minutes. (If the dough feels very sticky, knead in the remaining 1/4 cup of flour.)Lightly coat a large bowl with vegetable oil or cooking spray. Shape the dough into a ball, place it in the bowl, turn it to coat it with oil, and cover the bowl tightly with plastic wrap.

Let the dough rise in a warm place until doubled in size, about 1 hour.Turn the dough out onto an unfloured work surface and divide it in half with a sharp knife or pasty scraper. Shape each piece into a ball, cover with plastic wrap, and let rest for 15 minutes.Divide the marzipan or almond paste in half and roll each piece into a cylinder about 11 inches long; set aside. Pat each piece of dough into an oval measuring 12 inches long and 9 inches wide at its widest point. (If the dough sticks at any point, lightly dust it with flour.) Using the side of your hand, make a lengthwise depression down the center of each oval.

Place a cylinder of marzipan or almond paste in each depression. Lift 1 long side of each oval over the marzipan or almond paste to enclose it (as if closing a book), placing the top flap about 1 inch from the edge of the bottom flap. Line a baking sheet with parchment paper.

Place the stollen loaves on the baking sheet, leaving 3 inches of space between them. Cover with plastic wrap and let rise in a warm place until increased in volume by about half, about 45 to 60 minutes. Meanwhile, heat the oven to 350°F and arrange a rack in the lower third.Uncover the loaves and bake until browned and a thermometer inserted into the thickest part registers 195°F (test several spots because you may hit a pocket of marzipan), about 35 to 40 minutes. Meanwhile, melt the butter.

Transfer the loaves to a wire rack and immediately brush the loaves with the butter, using all of it.

Place 1/4 cup of the powdered sugar in a fine-mesh sieve and sift it over the stollen (there should be a generous coating). Repeat if the powdered sugar starts to melt in spots.

Let the bread cool completely, about 40 minutes. Before serving, dust with additional powdered sugar if necessary. To serve, slice into 1/2-inch-thick slices with a serrated knife.