Prep the pans and oven. Heat the oven to 350°F (175°C).
Line two 8-inch round cake pans with parchment and lightly grease the sides. You can also make one 9x13-inch sheet cake.
Whisk the dry mix. In a large bowl, whisk almond flour, coconut flour, whey isolate (if using), cinnamon, nutmeg, ginger, baking powder, baking soda, and salt. Break up any almond flour clumps.
Beat the wet ingredients. In another bowl, whisk eggs, sweetener, oil, almond milk, and vanilla until smooth and slightly frothy.
Combine to a batter. Pour the wet mixture into the dry and stir until just combined.
The batter will be thicker than traditional cake—this is normal.
Fold in the carrots and add-ins. Gently fold in grated carrots, nuts, and shredded coconut if using. Avoid overmixing to keep the cake tender.
Portion and bake. Divide batter evenly between pans. Smooth the tops.
Bake for 20–24 minutes for 8-inch rounds (25–30 minutes for 9x13) until the edges are set and a toothpick comes out clean or with a few moist crumbs.
Cool completely. Let cakes cool in the pans for 10 minutes, then transfer to a rack. Cool fully before frosting to prevent melting.
Make the frosting. Beat cream cheese and butter until fluffy. Add powdered sweetener, vanilla, and salt.
Beat until smooth, adding heavy cream 1 teaspoon at a time until it’s spreadable.
Assemble. Place one layer on a serving plate. Spread about 1/3 of the frosting on top. Add the second layer and frost the top and sides.
For a sheet cake, simply frost the top generously.
Chill briefly, then slice. Refrigerate 20–30 minutes to set the frosting for cleaner slices. Cut and serve.