Make lemon curd: In a small heavy saucepan whisk together yolks and sugar and whisk in lemon juice, butter, and a pinch of salt. Cook mixture over moderately low heat, whisking, until it reaches boiling point, 5 to 7 minutes (do not let it boil). Strain curd through a fine sieve into a bowl and cool, its surface covered with a plastic wrap. Chill curd, covered at least 4 hours or overnight. Make buttercream: In a heavy saucepan combine sugar and water and bring to a boil, stirring until sugar is dissolved. Boil syrup, undisturbed, until it reaches 248F on candy thermometer. While syrup is boiling, in a standing electric mixer beat whites with a pinch salt until foamy and beat in cream of tarter. Beat whites until they just hold stiff peaks and add hot syrup in a stream, beating. Beat mixture at medium speed until completely cool, 15 to 20 minutes. Beat in butter, 1 piece at a time, and beat until it is thick and smooth. (Buttercream will at first appear very thin but as more butter is beaten in, it will thicken.) Beat in lemon curd and salt, beating until smooth, and drizzle in framboise, 1 tablespoon at a time, beating. Buttercream may be made 4 days ahead and chilled in an airtight container or 2 weeks ahead and frozen in anairtight container. Let buttercream come completely to room temperature (this may take several hours if frozen) and beat before using. Makes about 12 cups. Gourmet September 1994