Preheat the oven to 350 degrees F (177 degrees C). Line the bottom of 2 9" round springform pans with parchment paper.
In a large bowl, beat together Besti and butter, until fluffy.
Beat in the eggs, one at a time. Stir in the vanilla, sour cream, almond milk, and vinegar first to prevent splashing, then beat to incorporate.
Reduce mixer speed to low and beat in the almond flour, ½ cup (56 g) at a time. Beat in cocoa powder and baking soda, until the batter is smooth. Beat in the beet root powder, if using, one teaspoon at a time to reach our desired color.
Divide dough among the 2 pans, and smooth the top with a spatula. Bake for about 25 minutes, until an inserted toothpick comes out clean. Cool completely in the pans, then run a knife along the sides and flip to release.
Make the keto cream cheese frosting according to the instructions here.
Place one layer of cake onto a cake stand or platter. Frost the top with ¾ cup (255 g) frosting. Place the second layer on top and frost the top with another ¾ cup frosting (255 g). Finally, frost the sides with 1 ½ cups (510 g) frosting. If desired, top with chopped pecans.
