Spray the phyllo shells with cooking spray and sprinkle with 2 to 4 tablespoons sugar. Place the shells on a baking sheet and transfer to the oven. Bake until golden brown, 5 to 10 minutes. Set aside and let cool completely.
Meanwhile, whisk the eggs, yolks and the 1/2 cup sugar in a bowl until thick and fluffy. Add the lemon zest and juice, and stir to combine.
Add the egg mixture to a heavy saucepan; heat over medium heat, stirring constantly, until thickened, 10 to 15 minutes. Pour into a bowl set in an ice bath. Stir in the butter, one pat at a time, and continue stirring to cool down quickly (or chill in the refrigerator until cool to the touch, about 5 minutes).
Fill a pastry bag or heavy-duty plastic bag with a corner snipped off with the lemon curd filling. Pipe the filling into the cooled tart shells, then freeze for 1 hour. Garnish with a small dollop of whipped cream and sprinkle with turbinado sugar just before serving.