- For the crust: Preheat oven to 350 F. Generously butter and flour a 9" fluted tart pan w/ a removable bottom and refrigerate it while the oven preheats.
- Remove the tart pan from the refrigerator. Use your fingertips to press the chilled pine nut dough evenly over the bottom and up the sides of the pan. Trim off any excess dough.
- Bake the crust for 10-15 mins, then rotate it and bake for another 10-15 mins, or until it is golden brown. Remove the crust from the oven and let it cool while you make the filling.
- For the sabayon: Bring about 1.5" of water to a boil in a pot that is slightly smaller than the diameter of the bowl you will be using for the sabayon. Meanwhile, in a large metal bowl, whisk the eggs, yolks, and sugar for about 1 min, or until the mixture is smooth.
- Set the bowl over the pot and, using a large whisk, whip the mixture while you turn the bowl (for even heating). After about 2 mins, when the eggs are foamy and have thickened, add 1/3 of the lemon juice, whisk, then continue adding another 1/3 until all the lemon juice is gone. Continue whisking vigorously, still turning the bowl, until the mixture is thickened and light in color and the whisk leaves a trail in the bottom of the bowl. (The trails should stay for a bit, instead of immediately disappearing.) The total cooking time should be 8-10 mins.
- Turn off the heat and leave the bowl over the water. Whisk in the butter a piece at a time. The sabayon may loosen slightly, but it will thicken and set as it cools. Pour the warm sabayon into the tart crust and place the pan on a baking sheet.
- Preheat the broiler. While the sabayon is still warm, place the tart under the broiler. Leaving the door open, brown the top of the sabayon, rotating the tart if necessary for even color; this will take only a few seconds, so do not leave the oven. Remove the tart from the broiler and let it sit for at least 1 hour. Serve at room temperature or cold.