1. In a food processor, pulse together flour and sugar. Add butter and pulse to a fine meal. Whisk together egg yolk and cream. Add to butter mixture and pulse until dough just comes together. On a lightly floured work surface, gently knead dough and flatten into a disk. Wrap in plastic and chill until firm, 2 hours.
2. Adjust rack to middle of oven. Heat oven to 375 degree F. On a lightly floured work surface, roll dough out to a 12-inch circle, 1/8 inch thick. Fit dough into a 10-inch tart pan and trim the pastry even with the edge. Freeze until firm. Bake until lightly golden in color, 10 to 12 minutes.Make filling::
3. Lower oven to 275 degree F. In a medium saucepan over medium heat, whisk together the lemon juice and sugar, and cook until sugar dissolves, 1 to 2 minutes. In a large bowl, whisk together eggs and cream. Remove lemon juice mixture from heat and slowly whisk in to egg mixture. Using a fine-mesh sieve, strain custard into the tart shell and bake until the center still jiggles a bit when gently shaken, 30 to 40 minutes.
4. Increase oven temperature to 350 degree F. Cut out a 10-inch circle of parchment paper, then cut into 8 individual wedges.Make meringue::
5. Whisk sugar and egg whites in a large mixing bowl over a saucepan of simmering water until smooth and warm to the touch. Remove from heat and whisk in flour. Spread meringue in a 1/8-inch-thick layer over each wedge of parchment paper. Transfer to a cookie sheet and bake until the meringue rises and the top is smooth and lightly brown, 10 minutes. Cool completely. Peel off parchment and set aside.
6. To serve, cut the tart into 8 pieces. Top each one with a meringue slice. Makes 8 servings.