1. Preheat the oven to 350°F (175°C). Line a 10×15 inch jelly roll pan with parchment paper, leaving a little overhang on the long sides, and lightly grease the parchment.

2. In a large mixing bowl, beat the eggs and granulated sugar together with a hand mixer or stand mixer on medium-high speed until the mixture is pale, thick, and slightly increased in volume, about 3 to 4 minutes.

3. Mix in the vanilla extract, milk, and vegetable oil just until combined.

4. In a separate bowl, whisk together the flour, cocoa powder, baking powder, and salt. Sift the dry ingredients over the egg mixture and gently fold with a spatula until no dry streaks remain, being careful not to deflate the batter.

5. Pour the batter into the prepared pan and spread it evenly into the corners with an offset spatula. Bake for 10 to 12 minutes, or until the top springs back lightly when touched and a toothpick inserted in the center comes out with a few moist crumbs.

6. While the cake bakes, lay a clean kitchen towel on the counter and dust it generously with cocoa powder or powdered sugar.

7. As soon as the cake is done, run a knife along the short edges if needed, then carefully flip the pan over onto the prepared towel. Peel away the parchment. Starting from a short side, roll the warm cake up with the towel inside to form a log. Let it cool completely in this rolled shape on a wire rack.

8. To make the filling, beat the softened cream cheese in a medium bowl until smooth. Add the powdered sugar, cocoa powder, and vanilla and mix until creamy.

9. Slowly pour in the 120 ml heavy cream while beating on medium-high speed until the mixture becomes thick, fluffy, and holds soft peaks. Do not overbeat.

10. Once the cake is completely cool, gently unroll it. Spread the chocolate cream filling evenly over the surface, leaving a small border around the edges.

11. Re-roll the cake, this time without the towel, into a tight log. Place it seam-side down on a wire rack set over a baking sheet and refrigerate while you prepare the ganache.

12. For the ganache, place the chocolate chips in a heatproof bowl. Warm the 180 ml heavy cream in a small saucepan over medium heat until steaming but not boiling, then pour it over the chocolate. Let sit for 1 minute.

13. Stir the cream and chocolate together until completely smooth, then add the butter and stir again until glossy. Allow the ganache to cool for 5 to 10 minutes until slightly thickened but still pourable.

14. Pour the ganache over the chilled log, letting it cascade down the sides. Use an offset spatula to smooth the top and create gentle ridges along the length if you like.

15. While the ganache is still tacky, sprinkle a line of red sanding sugar or sprinkles down the center of the log. Chill for at least 1 hour, or until the ganache is set.

16. Just before serving, lightly dust the top with powdered sugar if desired. Slice into spiraled rounds with a sharp knife, wiping the blade between cuts for the cleanest slices, and serve.