Prepare the Cake Batter Preheat your oven to 160°C or 320°F. Line a 30 x 40 cm baking tray with parchment paper. Separate the egg yolks and whites into two bowls. In a separate bowl, beat the egg whites and add the sugar until a fluffy meringue. Add the vanilla extract, and whisk until soft peaks form. Gently fold in the egg yolks into the egg white mixture. Fold carefully each time. Sift the cake flour and baking powder together, then gently fold into the egg mixture until fully combined. Add the oil and milk, folding in with a spatula in circular movements from the bottom of the bowl up, ensuring all liquids are fully incorporated.
Bake the Cake Pour the batter into the prepared tray, spreading it evenly. Bake for 18–20 minutes, or until a toothpick inserted comes out clean. Let the cake cool for 5 minutes, then flip it onto parchment paper to remove the lining. Allow it to semi-cool before rolling up. Turn the cake sheet around and wrap the roll carefully in the parchment and chill for 2 hours in the fridge.
Make the Filling In a mixing bowl, whisk together mascarpone, heavy cream, powdered sugar, vanilla extract mix until thick and creamy.
Assemble the Roll Take out the sponge and roll out gently. Lightly brush the cooled sponge with the coffee, be careful not to soak it complatly. Spread the mascarpone filling evenly across the sponge, reaching all the edges. Gently roll the cake from one short end, using parchment paper to help guide it into a tight roll.
Decorate Whip mascarpone, cream, vanilla, and powdered sugar until stiff peaks form. Spread over the chilled roll, making soft upward or downward strokes. Dust with cocoa powder and sprinkle with chocolate chunks if desired.