1. Preheat the oven to 350°F (180°C). Butter and flour two 8- or 9-inch (20-23cm) cake pans and line the bottoms with parchment paper.
2. To make the cake layers, sift together the flour, sugar, spices, baking soda, and salt. Set aside. With a handheld mixer or a stand mixer fitted with the paddle, beat the eggs until they are pale and frothy (they need not increase dramatically in volume). With the mixer running, drizzle in the oil and melted butter, then the vanilla.
3. Add the dry ingredients to the eggs and mix carefully until just combined. The paddle will accomplish this easily but if you only have a hand held mixer you may want to just do it by hand.
4. Fold in the carrots and raisins, then divide the batter between the two pans. Bake 30-35 minutes, until the surface springs back when gently touched. Cool the cakes completely before frosting.
5. To make the frosting, beat the cream cheese and butter together until smooth. Slowly add the powdered sugar (do this on low speed to avoid a dust cloud) and mix until light and silky. Add the vanilla.