Mix together dry ingredients (flour, baking powder, salt, cinnamon, nutmeg, and ginger) in a medium bowl; set aside.
In a large bowl, use a mixer to combine butter and brown sugar well. Add eggs and vanilla; stir until combined. Slowly (about ½ cup at a time) beat in dry ingredients until mixed well. Gently in carrots, pineapple, raisins, and walnuts.
Spoon batter onto greased cookie sheet and bake for 16-18 minutes, until tops of cookies are set and start to brown.
While cookies are baking, beat together butter and cream cheese for the icing. Add vanilla and salt. Slowly mix in powdered sugar until smooth.
Allow cookies to cool once removed from the oven. Make sandwiches with icing in the center of cookies.