Preheat your oven to 350°F. Lightly grease a 15x10-inch jelly roll pan and line it with parchment paper.

Make the sponge batter. Place eggs in the bowl of a stand mixer fitted with the whisk attachment and beat on high speed for 3 minutes until very frothy and doubled in volume. Add sugar one tablespoon at a time and beat for 5-8 minutes until pale, thick and tripled in volume. Mix in salt.

Whisk together milk, oil, vinegar and vanilla in a small bowl and gradually pour it into the egg mixture while mixing gently on low speed.

Sift flour and baking powder into a medium bowl and whisk to blend evenly. Then, sift it again over the mixer bowl with the beaten eggs in two parts and mix it in gently on low speed until just incorporated.

Spread the batter evenly into prepared pan using a large offset spatula. Bake for 12-15 minutes until lightly golden and it springs back when pressed gently.

Transfer pan to a wire rack to cool for a minute. Lay a tea towel onto a work surface. Sift icing sugar generously over the warm cake to cover the surface. Run a knife along the edges of the pan to release the cake, then carefully invert it onto a clean kitchen towel.

While the cake is still warm, gently roll it into a reasonably tight log starting from the short side. Let the cake cool completely in this rolled shape with the seam side facing down.

Make the filling. Combine cream, skim milk powder and sugar in a medium bowl and beat with an electric hand mixer until it forms firm peaks. Mix in vanilla.

Assemble the cake. Unroll the cooled cake and spread the jam or hot fudge sauce in a thin layer over the cake. Then, spread the cream filling over the surface leaving about ½-inch border. Gently roll up the cake with the filling.

Transfer it to a serving plate, cover with plastic wrap and refrigerate for at least 2 hours before serving. Dust with icing sugar before slicing.