Preheat the oven to 350°F. Grease a 9x9-inch baking pan and line the bottom with parchment paper.
In a medium bowl, combine the flour, baking powder, baking soda, cinnamon, nutmeg, cloves and salt.
In a large mixing bowl, cream the butter, brown sugar and granulated sugar. Beat in the eggs one at a time, mixing well after each. Add the vanilla extract and fresh orange zest.
Add the dry ingredients to the butter mixture in 2-3 batches, alternating with the orange juice. Mix gently until you have a thick, smooth batter. Be careful not to over-mix.
Toss the raisins, dried cranberries, dates and nuts with the remaining 1 Tbsp flour. Fold the fruit and nuts into the batter until evenly distributed.
Spoon the thick batter into the prepared pan and smooth the top with a spatula.
Bake for 50-60 minutes, or until the cake is dark brown and a toothpick inserted into the center comes out clean. If the top becomes too dark during baking, loosely cover with foil for the last 15 minutes.
Let the cake cool in the pan for 30 minutes, then invert onto a wire rack and let cool completely before cutting into squares.