Preheat oven to 350°F. Lightly grease two 8-in (2 L) round cake pans with butter or coconut oil; line bottoms with parchment paper. Set aside.
In large bowl, stir together almond flour, gluten-free flour, baking powder, cinnamon, baking soda and salt.
In another bowl, stir together carrots, applesauce, extra-virgin olive oil, sugar, oat milk, flaxseed, apple cider vinegar, vanilla and ginger. Stir into flour mixture; fold in pecans and raisins (if using). Scrape into prepared pans.
Bake until tops are firm and dry to the touch, edges are golden brown and skewer inserted into centre of cakes comes out clean, 33 to 37 minutes. Let cool in pans for 10 minutes. Carefully invert onto rack and let cool completely.
To assemble cake, place 1 layer top-side up on cake plate. Using offset spatula, spread one-third of the frosting over cake to the edge. Top with second layer, top-side up, and spread half of the remaining frosting over top. Spread the remaining frosting on side of cake.
Store cake, covered, in fridge until ready to serve to prevent frosting from melting.