My grandmother made this recipe when I was little and it was a family favorite, for sure. It is a cross between ice cream and semi freddo. I frequently tweak it and make it in my ice cream maker, or make it in a loaf pan to slice frozen, but here, in honor of my grandma and her patience, I am leaving the process exactly the way she did it, when the most advanced home cook's appliance was the iconic kitchen aid standing mixer. —navahfrost
Heat maple syrup to boiling point in small saucepan.
Beat egg yolks in the top of a double boiler until lemon yellow and thickened. Slowly add the maple syrup to the yolks, (temper them if you are worried about scrambling), whisking gently. Add the salt and continue whisking until thick. Pour it into a large bowl (the bowl of a standing mixer if you have one.). Refrigerate until completely cold.
Whip heavy cream until soft peaks form. Stir in vanilla.Gently fold the cream into the cooled maple mixture.
Beat egg whites until stiff but not dry. Fold the egg whites into the maple cream mixture.
Freeze the maple mousse in the bowl for one hour. Take it out and beat it with an electric mixer or standing mixer, and put the bowl back for another hour or two. Then beat it again and freeze it again. (Ah, the good old days. . . ) Enjoy!