Place the flour, sugar, butter, salt and lemon zest in a food processor fitted with a steel blade; process just until the mixture resembles coarse meal. Add egg yolk. With the machine running, add the lemon juice and water through the feed tube slowly and add just enough until the dough holds together and forms a ball. Add more flour if you need to- if it appears to be too sticky. Gather the dough, wrap it in plastic wrap, and refrigerate at least 2 hours.
Roll out the dough into a 14-inch circle on a lightly floured surface. Line an 11 or 12 inch tart pan with a removable bottom with the dough; trim and crimp the edges. Freeze the shell for 30 minutes.
Preheat oven to 425°F.
PREPARE THE FILLING:
In a medium bowl, toss the blueberries, sugar, cinnamon, butter and lemon juice together. Spoon the filling evenly into the tart shell.
Bake the tart for 12 minutes. Reduce the heat to 350° F. and bake until the berries are slightly soft, about 10 minutes. Let the tart cool completely.
Decorate the tart with 2 circles of fresh raspberries around the edge. Cut into 8 slices and serve with a dollop of whipped cream, if desired.