Beat eggs, milk, sugar, flour, cinnamon and vanilla in a large bowl just until blended. Stir in rhubarb. Roll out half the pastry to fit a 9-inch pie plate. Spoon in filling; dab with butter. Roll out remaining pastry; cut in 1/2 inch strips. Weave strips over filling for lattice top. Pinch top and bottom crusts together; turn under; pinch to make a stand-up fluted edge. Brush pastry with milk; sprinkle with sugar.
Bake at 400 degrees for 45 minutes or until pastry is golden brown.