01 - Preheat the oven to 350°F. Grease and flour a 9-inch round cake pan or line it with parchment paper.
02 - In a medium bowl, whisk together the flour, baking powder, baking soda, salt, cinnamon, and nutmeg. Set aside.
03 - In a large bowl, cream the softened butter and granulated sugar together until the mixture is light and fluffy.
04 - Beat in the large eggs one at a time, ensuring each is fully incorporated before adding the next. Stir in the vanilla extract and orange zest.
05 - Alternately add the prepared dry ingredients and buttermilk to the creamed butter mixture, beginning and ending with the dry ingredients. Mix until just combined, being careful not to overmix.
06 - Gently fold in the mixed dried fruits and nuts (if using) until they are evenly distributed throughout the batter.
07 - Pour the cake batter into the prepared pan and smooth the top surface evenly with a spatula.
08 - Bake for 45–50 minutes, or until a wooden skewer or toothpick inserted into the center of the cake emerges clean.
09 - Allow the cake to cool in the pan for 10 minutes before inverting it onto a wire rack to cool completely.
10 - Dust with powdered sugar before serving, if desired.