Preheat oven to 400°
Line a 15x11 jelly roll pan with parchment paper. Spray with non-stick and set aside.
Sift together the flour, cocoa and baking powder. Set aside.
Mix the eggs and sugar on high for 3-4 minutes.
Fold in the sifted dry ingredients.
Spread the batter evenly on the prepared jelly roll pan.
Bake for 7-8 minutes. Remove from oven and let cool for 1-2 minutes.
Sprinkle powdered sugar on a clean kitchen towel that has been spread out flat.
Invert the jelly roll pan onto the towel to release the cake. {Be very careful, I burned my hand during this step!}
Peel off the parchment paper.
Gently roll the cake {from the short side for a more spiraled middle}. Roll the cake and towel together.
Allow cake to cool completely.
Unroll the cake and spread the prepared buttercream frosting in an even layer.
Carefully roll the cake and the frosting together as firm as possible (without breaking the cake).
Refrigerate for 1-2 hours.
Top the rolled cake with chocolate ganache. Create a wavy tree bark pattern with the back of a spoon (or use a fork for a rougher bark effect)
Return cake to the fridge for 30 minutes or until the ganache is firm.
{optional} Sprinkle with powdered sugar. Garnish with fresh fruit, nuts or Cotton Candy Flames!