1. To Make Crust:.
2. Preheat oven to 350 degrees Fahrenheit (175 degrees Celsius).
3. Lightly grease a 9x13 inch baking dish.
4. In medium bowl combine butter, 1-1/2 cups of the flour and 1 tablespoon white sugar. Blend together with an electric mixer.
5. Press mixture into bottom of baking dish and bake for 15 minutes, until set.
6. To Make Filling:.
7. In large mixing bowl combine 6 egg yolks, 4 tablespoons flour, evaporated milk, 2 cups sugar and rhubarb.
8. Stir together and pour over cooled crust.
9. Bake for 1 hour, until set.
10. To Make Meringue:.
11. In large mixing bowl, beat 6 egg whites until foamy.
12. Beat in sugar and vanilla until stiff peaks form.
13. Spread meringue over rhubarb and bake 10 to 20 minutes, until golden.