1) Preheat your oven to 325°F. Lightly grease a baking sheet, or line it with parchment paper.
2) Whisk together the flour, sugar, baking powder, salt, and spices in a mixing bowl.
3) Cut the cold butter into small chunks, then blend it into the flour mixture to form uneven crumbs.
4) In a separate bowl, mix together the pumpkin, egg, and vanilla.
5) Toss the fruit and nuts with the flour mixture until evenly distributed. Then combine the wet and dry ingredients, mixing until most of the flour is moistened.
6) Turn the dough out onto a lightly floured work surface, and knead it two or three times, until it holds together. Divide it in half; if you have a scale, each half will weigh slightly more than a pound (about 467g).
7) Roll each piece of dough into an 8" x 7" oval about 1/2" thick.
8) Fold each piece of dough roughly in half, leaving the edge of the top half about 1/2" short of the edge of the bottom half. Should you fold the long way, or the short way? The long way will give you a longer, narrower stollen, with shorter slices; folding the short way will give you a wider, fatter stollen, with longer slices.
9) Use the edge of your hand to press the dough to seal about 1" in back of the open edge; this will make the traditional stollen shape. It's also the familiar Parker House roll shape, if you've ever made them.
10) Place the shaped stollen on the prepared baking sheet.
11) Bake the stollen until they're very lightly browned around the edges, about 40 minutes. A cake tester inserted into the center should come out clean; and an instant-read thermometer will register about 205°F.
12) Remove the stollen from the oven, and transfer to a rack. Brush thoroughly with about half the melted butter. Sprinkle heavily with confectioners' or non-melting white sugar.
13) Allow the stollen to cool, then brush with the remaining butter (you'll have to reheat it), and sprinkle with the rest of the sugar. Let set for an hour or so, then wrap loosely in plastic wrap until ready to serve. Plastic-wrapped stollen will keep well for about a week at room temperature. For longer storage, omit the second butter/sugar coating; wrap well, and freeze for up to a month. Just before serving, sprinkle with sugar again.
Yield: two 1-pound stollen loaves.