Preheat the oven to 350 degrees F. Line mini cupcake pans with cupcake liners.
In a small bowl, sift together the flour, baking soda, cinnamon and salt. Set aside. In a large bowl, beat together the eggs while adding the oil, buttermilk, sugar and vanilla one at a time. Mix until well incorporated. Slowly add the flour mixture into the large bowl to combine. Stir in the pineapple, carrots, coconut, raisins and walnuts.
Scoop the batter into the prepared cupcake pans, filling each cup about three-quarters of the way full. Bake for 12 to 15 minutes, rotating the pans after 6 or 7 minutes (see Cook's Note). Let the cupcakes cool completely before frosting with the Cream Cheese Frosting. Garnish with additional chopped walnuts.
Cream Cheese Frosting:
In a stand mixer with the paddle attachment, beat the butter, cream cheese and confectioners' sugar. Then slowly add in the milk, vanilla and orange zest and juice and mix until combined.
You can use regular cupcake pans if you prefer, though the baking time will be longer, about 20 minutes.