For the sponge:
For the jam:
Preheat the oven to 350°F.
Oil a baking pan and cover with a baking sheet. Sprinkle oil over the sheet once more and set aside.
Sprinkle some powdered sugar on a kitchen cloth in a 4 x 6-inch rectangle. Set aside.
In a small bowl, mix the almond milk and vinegar, set aside so it curdles for a few minutes, and then add the flaxseed flour. In a large bowl, mix the flour, sugar, cornstarch, baking powder, xanthan gum, baking soda, and salt. Make a hole in the middle and pour the oil, vanilla extract, and almond milk mixture. Beat for 10 seconds.
Put the dough in the baking pan with the baking sheet and smooth the surface. Bake for 12 to 13 minutes, or until you can insert a toothpick into it and it comes out clean.
Allow to cool for 3 minutes and then turn over into the prepared kitchen cloth. Remove the paper and fold the remaining of the cloth over the edge of the cake and roll carefully. Tuck the edges underneath and allow to cool.
For the mousse, blend all the ingredients except for the chocolate until getting a homogeneous paste. Melt the chocolate in a bain-marie and blend with the rest of the ingredients to process until everything is uniform. Put in a bowl and allow to cool for at least 30 minutes at room temperature.
For the jam, put the raspberries and sugar on a small pot over medium heat until it boils and keep over the heat for 10 minutes, allow to cool.
Unroll carefully, trying not to squash the sponge completely. Spread the chocolate mousse and raspberry jam over it. Roll again and leave the seam downwards in a serving platter, placing it on the flat side of the previous roll.
For the mocha cream, put the butter, cream, and sifted powdered sugar in a bowl. With a hand mixer, beat until the cream is soft and homogeneous, this will take about 8 minutes. Then add the rest of the ingredients and beat for about 3 more minutes.
To assemble, cut both ends diagonally and place the cut pieces as branches. Cover with the butter and mocha cream Use a fork along the trunk to draw a texture and cut the branches so it looks like tree bark. Decorate with some sliced almonds and raspberries.