Combine all the ingredients in a cooking pot.

Bring the mixture to a boil over medium heat and cook for around 20–25 minutes, stirring occasionally. To check for doneness, coat a spoon with the jam and quickly trace a line across the back of it with your fingertip.

Pour the hot jam into a clean bowl, cover with plastic wrap, and freeze until cold but not frozen.

Preheat the oven to 355F (180C). Line an 11 x 16-inch (28 x 40 cm) jelly roll pan with parchment paper so the bottom and sides are covered. Use nonstick silicone-coated parchment, a Teflon mat, or a perforated silicone mat. Alternatively, fold parchment paper to create a pan of the required size with sides about 1 inch (2 cm) tall, then place it on a baking sheet.

In a large bowl, combine the egg yolks, milk, oil, and vanilla extract. Whisk until well mixed.

Sift in the flour and salt. Whisk until smooth and no dry ingredients remain.

In another bowl, add the egg whites, cream of tartar, and sugar. Whip with a hand mixer, gradually increasing the speed, until medium peaks form.

Fold one-third of the egg white mixture into the egg yolk mixture until combined.

Add the remaining egg whites and gently fold until the batter is homogeneous.

Pour the batter into the prepared pan and spread it evenly using an offset spatula. Bake for 12–15 minutes, or until the top just begins to turn lightly golden.

Remove from the oven and let rest for 1 minute. Turn the cake out onto a fresh sheet of parchment paper and carefully peel off the parchment from the bottom.

Allow to cool completely and cut into two even pieces before assembling.

Into a bowl, add all frosting ingredients. Whip with a hand mixer to stiff peaks. Be careful not to overwhip the cream! Place the cream into a piping bag and cut off the end.

Place one layer of the sponge cake onto a serving plate. Add approximately ½ cup of the strawberry jam and spread in an even layer.

Pipe ⅔ of the frosting in an even layer on top of the jam layer. Gently even it out with an offset spatula. I don't advise dumping the frosting in one spot and then trying to spread it over the jam — the cream will slide on top of the jam. Alternatively, if you don't have a piping bag, you can apply the frosting first in an even layer and then spread the jam on top.

Place the second sponge cake layer on top and apply the rest of the frosting on top in an even layer. Place into the fridge for 4–6 hours.

Slice the cake into 10 even pieces and decorate each piece separately or decorate the whole cake as one. I sliced mine into 10 pieces and piped some strawberry jam on top.