Mini X'mas Chocolate Log Cake

I am submitting this to Bake-Along #56 : Theme - Christmas Log hosted by Lena of Frozen Wings, Joyce of Kitchen Flavours and Zoe of Bake for Happy Kids.

Recipe

Ingredients
Sponge cake:
4 egg (separated)
1 egg yolk
75g sugar
65g cake flour
1/2tsp baking powder
20g chocolate (melted)
10g cocoa powder
50g butter

Ganache:
150g whipping cream
100g cooking chocolate (chopped)
20g butter

Steps:
Ganache:
1. Melt chocolate and whipping cream together in a double-boiler over a simmering water.
2. Add in butter and stir till melted.
3. Leave aside to cool, cover and store in fridge till it set to a spreadable consistency.

Sponge cake:
1. Preheat oven to 190C.
2. Lined and greased a 11" by 14" tray and set aside.
3. Melt butter, stir in melted chocolate and cocoa powder till well blended.
4. Sift cake flour and baking powder together, set aside.
5. Use a cake mixer, whisk egg whites till frothy.
6. Gradually add in sugar and whisk till medium stiff peaks form.
7. Switch speed to medium and gradually add in egg yolks and whisk for another minute until well combined.
8. Fold flour into the meringue lightly in 3 portions until well blended.
9. Pour some cake batter into chocolate mixture and stir till well mix.
10.Pour chocolate batter into the cake batter and fold in lightly till blended.
11.Pour batter in the prepared tray and smooth surface.
12.Bake in a preheated oven for 14mins.
13.Remove cake from tray and cool on a rack.

Assemble the cake:
1. Cut sponge into two pieces.
2. Carefully transfer one piece onto a greaseproof paper.
3. Spread ganache on cake.
4. Gently roll the cake by using the paper to lift the cake and guide roll.
5. Wrap up the swiss roll in a greaseproof paper.
6. Repeat steps no.2-5 for the other sponge.
7. Rest both rolls in the fridge to stabilize it shape.
8. Spread ganache on rolls, use a small fork and draw pattern on rolls.
9. Return rolls in fridge again till ganache set.
10.Slice, decorate and serve.