01 - Preheat the oven to 350°F. Line an 8-inch round or square baking pan with parchment paper, or grease lightly with cooking spray.
02 - Place the oats in a blender or food processor. Pulse until they reach a coarse, flour-like texture, about 30-45 seconds.
03 - In a medium mixing bowl, whisk together the processed oat flour, baking powder, baking soda, cinnamon, nutmeg, and salt until evenly distributed.
04 - In a separate large bowl, whisk the eggs, maple syrup (or honey), melted coconut oil, and vanilla extract until smooth and well combined.
05 - Add the dry ingredients to the wet ingredients. Stir with a spatula or wooden spoon until just combined—do not overmix.
06 - Gently fold in the grated carrots, raisins, and nuts (if using) until evenly distributed throughout the batter.
07 - Transfer the batter to the prepared pan. Use a spatula to spread it evenly, reaching into the corners.
08 - Bake for 35-40 minutes, or until a toothpick inserted in the center comes out clean or with just a few moist crumbs.
09 - Allow the cake to cool completely in the pan before slicing into squares or wedges and serving.