Prepare a 7 inch round deep cake pan by lightly buttering the interior and lining the bottom with parchment paper
Place the prepared cake pan into the refrigerator during the remaining prep time
Separate the eggs into whites and yolks
Place the egg whites into the refrigerator
Place 200 grams of cream cheese into a large bowl and stir until smooth with a stiff wooden spoon
Add the heavy cream and whisk until smooth
Add the whole milk and whisk until smooth
Add the sugar and egg yolks (one at a time) and whisk until they are all fully incorporated
Pass the batter through a mesh strainer to avoid any clumps
Whisk in the lemon juice and lemon zest
Sift the flour and cornstarch into the batter and mix until everything is fully incorporated
Preheat the oven to 340 degrees
Place the cold egg whites into a clean, dry bowl and begin beating them on medium high speed
Once the surface of the egg whites is covered in large bubbles, add the cream of tartar
Continue beating on medium high and gradually add the sugar
Beat on medium high until the egg whites will hold stiff peaks
Add 1/3 of the whipped egg whites to the batter and mix gently. Be careful not to break down the egg whites as you mix
Add another 1/3 of the whipped egg whites and once they are combined, add the remaining egg whites and mix until just incorporated, no more
Pour the batter into the cold prepared cake pan, filling it to 1/2 inch from the top of the pan (you may have a bit of batter left over, but do not fill the pan to the top or it will overflow as it rises)
Bang the cake pan onto the counter top a few times to work any air bubbles up to the top surface of the batter
Prepare a water bath by placing the round cake pan into a rectangular cake pan and add enough hot water to the rectangular pan to come half way up the side of the round pan
Carefully place the pans into the oven on a middle rack
Reduce the heat to 325 degrees
Bake at 325 degrees for 20 minutes
After 20 minutes have elapsed, put the timer on for 55 minutes and reduce the heat to 285 degrees without opening the oven door (*Don't worry if this takes 20 minutes or so, just leave the oven door closed as the temperature slowly reduces)
After 55 minutes have elapsed, put the timer on for 30 minutes and turn the oven off without opening the oven door
After 30 minutes have elapsed, put the time on for 20 minutes and crack the oven door open about 2 inches (If your door wants to close, prop it open by placing a folded towel in between the door and the door frame)
Remove the pans from the oven and carefully remove the round pan from the water bath
Place the cake (still in the cake pan) into the refrigerator in an airtight container for 4 or more hours to chill
Carefully remove the chilled cake and place it onto a flat surface
Dust with confectioners sugar, top with berries and whipped cream (optional) and cut into slices
Serve chilled