Heat oven: To 350°F (175°C). Line the bottom and sides of a 9×13-inch cake pan with parchment, and coat it lightly with nonstick cooking spray.

Make the meringue: In the large bowl of a stand mixer fitted with the whisk attachment, or with a hand mixer, beat the egg whites with ¼ teaspoon salt on medium/low speed until they begin to thicken. Increase the speed to medium, and add half the sugar — ¾ cup — a little at a time. Add ½ teaspoon vanilla extract or paste and continue to whip the mixture until the egg whites are glossy, and stiff peaks form when the whisk is lifted.

Make the cake: In a second bowl, beat the butter with the remaining ¾ cup sugar, remaining ¼ teaspoon salt, remaining ½ teaspoon vanilla, and all of the lemon zest until light and fluffy. Add egg yolks and beat to combine. Sprinkle surface of batter with baking powder and beat thoroughly into mixture. Add the milk and beat to combine; the batter will look curdly. Add the flour and beat until smooth.

Bake the cake: Spoon the cake batter into the bottom of your prepared cake pan and spread it into a thin, even layer. Dollop the egg white mixture all over the batter and gently spread this across the cake. Bake for 20 minutes, then check for doneness. The cake might need 5 to 10 minutes longer to set.

Once baked, cool cake in pan for 10 minutes, then transfer to a cooling rack to completely cool.

Finish cake components: In a medium bowl, combine strawberries, 1 tablespoon of the sugar, and lemon juice and set aside. Combine the heavy cream, crème fraîche, remaining 1 tablespoon sugar, and vanilla extract or paste in a large bowl, and beat until soft peaks form.

Assemble the cake: Carefully cut the cooled cake in half the long way. Transfer the first half onto a plate, swirl with half the whipped cream, then scatter with half the berries. Place the second half of the cake on top and finish with remaining cream and berries. Garnish with mint leaves and/or powdered sugar, if desired.

To serve: Store the cake in the fridge until needed. Cut into slices to serve. Leftovers keep in the fridge for 4 days.