Whisk together almond flour, coconut flour, sweetener, baking powder, baking soda, cinnamon, nutmeg, ginger, and salt in a large bowl.
In a separate bowl, whisk the eggs, then add melted butter, heavy cream, and vanilla extract until fully combined.
Pour the wet ingredients into the dry ingredients and mix until smooth; the batter will be thick.
Fold in shredded carrots and nuts (if using).
Preheat oven to 350°F (175°C). Grease or line an 8-inch pan and spread the batter evenly.
Bake for 30–35 minutes, or until a toothpick comes out clean and the top springs back.
Let the cake cool completely before frosting.
Beat cream cheese and butter until creamy, then add powdered sweetener and vanilla.
Add heavy cream, 1 tablespoon at a time, until the frosting becomes fluffy and spreadable.
Spread frosting over the cooled cake, slice, and serve.