In the bowl of a stand mixer fitted with the paddle attachment, beat butter and sugar at medium speed until creamy, 3 to 4 minutes, stopping to scrape sides of bowl. Add Marzipan, and beat until well combined. Beat in egg yolk. Beat in zest and vanilla bean seeds.

In a medium bowl, sift together flour, salt, nutmeg, and ginger. With mixer on low speed, add flour mixture to butter mixture in 2 additions, letting first addition fully incorporate before adding the second. Stir in Rum-Soaked Fruit. Turn out dough, and shape into a 7-inch square. Wrap in plastic wrap, and refrigerate for 30 minutes.

Preheat oven to 325°F (170°C). Line a baking sheet with parchment paper.

Between 2 sheets of parchment paper, roll dough into a 9-inch square. Freeze for 15 minutes. Using a sharp knife, cut dough into 2¼×1½-inch rectangles. Place 1 inch apart on prepared pan. (If dough starts to soften, place back in freezer until firm again.)

Bake until lightly browned, 15 to 17 minutes. Let cool on pans for 3 minutes. Remove from pans, and let cool completely on wire racks. Pipe Rum Glaze over cooled cookies.