Prepare Pastry: Place flour, salt, cream of tartar and butter in food processor. Whirl until texture of coarse meal. Add water. Whirl just until combined and mixture begins to mass together. Place on plastic wrap, flatten to a disk, and wrap airtight. Refrigerate at least 1 hour or up to 30 days.
Roll dough on floured surface to 1/8" thickness. Cut out 24 circles with 3" round cookie cutter, rerolling scraps; or trace around 3" water glass. Pleat edges of circles and fit in bottom of muffin tins.
Prepare Filling: Beat egg in bowl. Add Meunster, Cheddar, Parmesan, parsley, chives and mint. Spoon 2 teaspoons filling in each pastry shell; spread level. (Can be prepared up to 3 hours ahead and refrigerated.)
Bake in preheated hot oven (425'F) for 12-15 minutes or until the filling is golden brown and the pastry begins to color. Remove from tins; cook on rack. Serve warm.