Process raisins and ginger in food processor until mixture sticks together and only small pieces remain, 10–15 seconds. Transfer mixture to a large bowl.
Melt butter in small saucepan over medium heat, swirling saucepan occasionally, until nutty brown in color, about 8 minutes. Stir in cinnamon and allspice and cook until fragrant, about 15 seconds. Stir butter mixture into raisin mixture until well combined; let cool completely.
Whisk flour, baking soda, and salt together in a bowl.
Whisk brown sugar, molasses, and eggs into cooled butter-raisin mixture until incorporated.
Using a rubber spatula, fold in flour mixture and nuts (dough will be very sticky). Cover bowl with plastic wrap and refrigerate until dough is firm, at least 1½ hours or up to 24 hours.
Adjust oven racks to upper-middle and lower-middle positions and heat oven to 350ºF (176ºC). Line 2 baking sheets with parchment paper.
Transfer dough to a lightly floured surface and divide into quarters. Roll 1 piece of dough into a 10-inch log on lightly floured surface. Transfer log to prepared sheet, brush off any excess flour, and tap ends with a ruler to neatly square (each sheet will contain 2 logs). Repeat with remaining dough.
Bake cookie logs until only a slight indentation remains on edges when touched (center will appear slightly soft), 16–20 minutes, switching and rotating sheets halfway through baking. Let cookies cool on sheets for 5 minutes, then slide cookies, still on parchment, onto wire rack. Let cookies cool completely.
Whisk together confectioners' sugar, orange juice, zest and pinch of salt in small bowl until smooth. Drizzle glaze onto cooled cookies and let sit until glaze dries, about 15 minutes.
Cut cookies into 1½-inch bars before serving.