Line a 9x9x2-inch baking pan with foil, extending the foil over edges of pan. Lightly coat foil with cooking spray. Set pan aside.
In a large bowl, combine vanilla wafer crumbs, the 3/4 cup powdered sugar, the cocoa powder, cinnamon, and cloves. Stir in melted butter and rum until well combined. Stir in candied fruits, raisins, hazelnuts, and dates; mix well.
Press mixture into prepared pan. (Mixture will be slightly sticky.) Cover and refrigerate overnight.
Lift cake from pan using the foil and place on cutting board. Remove foil. Coat a long sharp knife with cooking spray and cut cake into 1-1/4- to 1-1/2-inch diamonds or squares. Sift powdered sugar over diamonds just before serving. Makes about 20 diamonds.
Place bars in a single layer in an airtight container; cover. Store in the refrigerator for up to 3 days. Do not freeze.