1. Heat the oven to 200C/fan 180C/gas 6. Arrange the squash on a baking tray or in a roasting tin, lightly sprinkle with water, then cover tightly with foil. Bake for 40-45 mins until soft. Drain off any liquid, then transfer to a bowl and whisk the squash with a hand blender until a smooth purée. Set aside to cool completely. When ready to use, drain the purée and weigh out 150g.
2. Turn the oven down to 180C/fan 160C/gas 4. Grease and line a 23 x 33cm swiss roll tin or baking tin with baking parchment, making sure the sides are covered. In a large bowl, mix the Dr. Oetker Fine Dark Cocoa Powder, caster sugar, Dr. Oetker Baking Powder and Dr. Oetker Bicarbonate of Soda. In a jug, stir together the squash purée, vegetable oil and 125ml of water. Add to the dry ingredients, stir to combine, then pour into the prepared tin. Bake for 20-25 mins until firm.
3. Place a sheet of baking parchment onto your work surface and sprinkle over the extra caster sugar. Once the sponge is baked, turn it straight out onto the sugared baking paper. Leave for a few mins until it’s just cool enough to handle, then roll it from the long side using the sugared paper. Leave to cool completely.
4. To make the filling, put the dairy-free spread in a large bowl and beat with an electric whisk until pale and fluffy. Add half the icing sugar, whisking until fully combined, before adding the rest of the sugar along with the Dr. Oetker Madagascan Vanilla Extract. Beat again until light in colour. Set aside a third of the buttercream, then add the Dr. Oetker Fine Dark Cocoa Powder to the rest, beating in well. If needed, add 1 tsp of milk to loosen the mixture.
5. Once the cake is completely cool, unroll gently. Spread the white buttercream all over, then scatter over the cherries. Roll the sponge back up and cut off a diagonal slice. Place the main cake onto a serving plate and add the smaller piece to make a ‘branch’. Spread the chocolate buttercream all over the yule log and run a fork through it to create a bark effect. Sprinkle with a little icing sugar and decorate with fresh or dried cranberries and sprigs of rosemary.