A semifreddo is a cross between ice cream and mousse, but doesn't require any special equipment to prepare. The texture is smooth and luxurious when allowed to sit at room temperature until it just on the verge of melting, but still partially cold, hence the name.
Line a loaf pan (9x5 Loaf Pan or 9x4 - Pullman pan, which is what I used to create the square shape) with plastic wrap.
In a saucepan, cook the cherries until they release their juices (this will take longer with fresh cherries), about 5-10 minutes. Whisk together 1 1/4 cups (285g) sugar and cornstarch, then add it to the cherries, cook for 3 minutes or until the juices are thick and clear. Allow to cool. Puree half the mixture until smooth and refrigerate.
Whip the heavy whipping cream to soft peaks - don't over whip or they will not blend well into the mixture.
Whip the egg yolks in a stand mixer, fitted with a whip attachment, until light in color on high speed, about 3 minutes. While they are whipping, heat the milk with the remaining sugar until simmering. Turn down the speed of the mixer to low and slowly drizzle the hot milk into the whipping egg yolks. Turn back to high speed and whip until light, fluffy and cool to the touch.
Fold the cooled pureed cherries into the egg mixture. Fold the whipped cream into the cherry/egg mixture.
Pour 1/3 of the mixture into the prepared pan. Add 1/3 cup of the whole cherries to the pan. Add another 1/3 of the semifreddo mixture to the pan and another 1/3 cup fruit over that. Repeat with the remaining semifreddo and 1/3 cup cherries. Cover and freeze for several hours or overnight, until very firm.
Invert the semifreddo onto a frozen serving tray, return to freezer.
Once the semifreddo is firm, make the topping. To make the Swiss Meringue: Bring about an inch of water in a saucepan to a simmer. Combine the egg whites, sugar and salt in the bowl of a stand mixer. Place the bowl over the simmering water and stir the egg mixture with a rubber spatula until it is hot and all of the sugar has dissolved, about 5 minutes. Remove from heat and place the bowl onto the stand mixer, fit with a whisk attachment. Beat on high speed until very think, glossy and stiff peaks when you lift the beater. See my "101 meringue" video on instagram to watch me make the Swiss Meringue. Make sure the meringue is cool to the touch, add the passion fruit powder and beat for another minute.
Spoon the meringue over the semifreddo and return to the freezer to set for at least an hour before serving.
Top with some of the remaining cherries, slice the semifreddo and allow it to sit on the plates for 10+ minutes before serving. Add more cherries.
If you don't have superfine sugar, just blend granulated sugar in a food processor for 2 minutes.