• Preheat your oven to 325 °F (165℃) and prepare a jelly roll pan by greasing it well and lining the bottom with a piece of parchment paper. It's also a good idea to grease the top of the parchment paper.
• Add the egg yolks and sugar and whisk them with a hand mixer until the mixture is light and creamy and the sugar grains have disappeared.
• Add the oil, milk and vanilla extract and incorporate them well. Set the bowl to a side.
• Sift the flour, cornstarch and baking powder in another bowl and mix them well with a fork.
• To another clean and dry bowl, add the egg whites with the salt and whisk them until soft peaks form. Add the cream of tartar and whisk very well until you get strong and sturdy hard peaks.
• Over the egg whites add 1/2 of your egg yolks mixture and 1/2 of your flour mixture and fold them in gently. Repeat the process with the rest of the egg yolk mixture, folding them as gently as possible to not deflate the egg whites.
• Pour the batter into the prepared jelly roll pan and spread it out to the edges being careful to spread the batter as evenly as possible. Bake at 325℉ (165℃ ) for about 13-15 minutes or until a toothpick inserted into the middle of the cake comes out clean.
• As the cake bakes, dust powdered sugar generously over a clean kitchen towel creating a rectangle shape, slightly larger than your jelly roll pan.
• Immediately after taking the cake out of the oven, drag a butter knife along the edges of the cake to make sure all the edges come loose from the pan. Line a cooling rack with parchment paper and place it upside down on top of the hot cake before inverting. Invert it again so the cake is face down on top the kitchen towel over the powder sugar. Peel off the parchment paper from the bottom of the cake.
• Roll the cake with the towel inside the roll as well, from the narrow end, while it's hot from the oven. Don't roll it too tightly or aggressively, but the cake should be firmly rolled with no spaces on the inside of the roll.
• Let the cake roll cool, rolled, turning it several times throughout the cooling process so that it keeps a round shape and doesn't flatten on one side. This should take about one hour to one hour and a half.

For the frosting:

• Add the room temperature cream cheese, butter and mascarpone to the bowl of your stand mixer fitted with the paddle attachment (or in a bowl with your hand mixer). Whip them on medium high speed until they're creamy and smooth.
• Sift the powdered sugar and slowly add it, one cup at a time, mixing after each addition. Add the salt and mix until incorporated.
• In another bowl, whip 1/2 cup of heavy cream (this will yield 1 cup of whipped cream). Add it to your mixture and fold it in gently.

Assembly:

• Once the frosting has reached the right consistency and the cake has cooled completely, gently unroll the cake (you don't need to flatten it completely - one end will have a small curl). With an offset spatula gently spread a thin layer of strawberry jam on the whole cake. Add a couple of dollops of frosting and spread it out evenly to a thickness of about 1/3-1/2 inch, leaving the last 1/2 inch of the cake on the narrow end (the flat end) free of frosting. Add a little bit of extra frosting under the curled up end.
• Gently roll your cake back up without the towel. Wrap it tightly in plastic wrap and put it in the fridge for an hour or pop it in the freezer for 20 minutes to set.

Serving:

• After the frosting has firmed up in the fridge or freezer, remove the plastic wrap, cut 1/4-inch slices from each raw end of the Swiss roll and dust the top with powdered sugar.
• Slice and serve.