Preheat oven to 325 degrees F. Generously butter a square 8-inch pan. Or line it with parchment with an overhang and spray with oil.
In a large bowl, whisk together the eggs, oil, and stevia until combined.
Mix in the almond flour, using a rubber spatula and then a hand whisk. Whisk until completely smooth.
Whisk in the cinnamon, allspice, kosher salt, and baking powder.
Fold in the grated carrots.
Transfer the batter to the prepared pan, smoothing it out with a rubber spatula. Bake until puffed and fragrant and a toothpick inserted in center comes out clean, about 25 minutes.
Cool in pan on a cooling rack until completely cool, about 1 hour.
When cake is completely cool, make the frosting: whisk the soft cream cheese, stevia and vanilla with a hand whisk until smooth and fluffy.
Run a knife around the edges of the pan to loosen the cake. Cut the cake into nine squares. To remove each square from the pan, firmly slide a cake server underneath each slice and lift it out.
Using a soup spoon, divide the frosting evenly between the cake slices. Use a small spatula to spread the frosting evenly on top of each slice (just like you would frost a cupcake).
* A granulated sweetener in the frosting will feel grainy - so please use a powdered sweetener. If using a powdered sweetener in the frosting instead of stevia, it's possible that you would need to add a bit more heavy cream to get the right consistency.