Slice the cake into six 1/2-inch-thick slices. Cut six (2 1/2-inch) circles--one from each slice--with an unfluted round cookie cutter, discarding the scraps. (You can also use a small knife.) Place the cake rounds 2 inches apart on a flat dish that will fit in your freezer.
Soften the sorbet and ice cream just enough to be able to scoop them with a standard 2 1/4-inch-diameter ice cream scoop (15 to 30 seconds in the microwave works). Fill half the scoop with raspberry sorbet and the rest of the scoop with vanilla ice cream and place an ice cream ball, flat side down, in the middle of each cake round. Freeze for at least 30 minutes, until the ice cream is very hard.
Preheat the oven to 500 degrees F.
To make the Swiss meringue, place the egg whites and sugar in a heat-proof glass bowl set over a pan of simmering water. Whisk the mixture almost constantly, until it reaches 120 degrees F on a candy thermometer and the sugar has dissolved. Pour the mixture into the bowl of an electric mixer fitted with the whisk attachment. Add the vanilla, cream of tartar, and salt and beat on medium speed for one minute, then on high speed for 5 minutes, until the egg whites form stiff, glossy peaks.
Transfer the cake rounds and ice cream to a sheet pan lined with parchment paper. Working quickly, spread the meringue with a spoon or small spatula, making lots of peaks all over with the back of the spoon. (You can also use a pastry bag fitted with a large fluted tip and pipe the meringue thickly around each ball of ice cream and cake.) Be sure all of the ice cream is covered with meringue. Bake for 2 1/2 to 3 minutes, until the edges of the meringues are browned, turning the pan once to brown evenly. Transfer to dessert plates, drizzle Fresh Raspberry Sauce around each baked Alaska, and serve immediately.
Fresh Raspberry Sauce:
Place the raspberries, sugar, and 1/4 cup water in a small saucepan over medium heat. Bring to a boil, lower the heat, and simmer for 4 minutes. Pour the cooked raspberries, the jam, and the framboise into the bowl of a food processor fitted with the steel blade and process until smooth. Pour into a container and chill. The sauce can be refrigerated for up to one week.