In a large bowl, use an electric mixer to beat together butter, cream cheese, cocoa powder, salt, and confectioner erythritol.
Slowly add in your heavy cream, beating the frosting as your pour it in until it is fully combined.
Keep the frosting at room temperature while the cakes bake.
Let the cakes cool for 10 minutes once they come out of the oven.
Use a scissors to cut out 6-8 medium sized triangles of parchment paper. Place them on your cake stand or plate so that they resemble pie wedges.
Carefully invert one of your cake layers and place it on top of your parchment lined cake stand.
Spoon about 1 cup of frosting on top of the cake layer and slowly smooth it on.
Carefully flip your second cake layer upside down to remove it from the tin and place it on top of the first layer.
Take another 1 cup of icing and smooth it over the top of the second layer.
Carefully remove the third cake layer from it's tin and place it on top of the second layer.
Take the remaining icing and cover the top and sides completely. (Using an off-set spatula helps with this.)
Slowly and carefully, remove the parchment paper triangles from under the cake and discard.
Place your nest on top of the cake and perch your raven.
Decorate with flowers, spiders, or bugs.