Preheat the oven to 350º and spray a rimmed baking sheet with non-stick cooking spray. Set aside. In a medium size mixing bowl, stir the flour, cinnamon, cloves, salt and baking soda till combined. In the bowl of a stand mixer fitted with the paddle attachment, mix the sugar, canola oil, sour cream and eggs over low speed until thoroughly combined. Add the flour mixture to the bowl of the stand mixer and again mix on low to combine. Add the pineapple, walnuts and carrots to the stand mixer and mix until just combined. Using a rubber spatula, spread the cake batter evenly in the prepared baking sheet. Bake for 25-30 minutes, until a toothpick inserted in the center removes clean. Allow to cool to room temperature and then refrigerate uncovered for 1 hour. After chilling, frost the carrot cake bars and return them to the refrigerator for at least 2 hours to chill. Cut into squares and serve.