Step 1Brush edges of Master pie shell with egg white.
Step 2Combine sugar and cornstarch. Beat yolks with wire whisk until light and fluffy. Stir into cornstarch mixture. Mixture will look somewhat crumbly, almost streusel-like. Toss with rhubarb and spoon evenly into crust. Sprinkle with nutmeg.
Step 3Bake at 350 degrees until center is set, 50 minutes to 1 hour.
Step 4Remove pie from oven and top with meringue, spreading evenly over filling to edges and using back of spoon to swirl. Bake at 400 degrees until Meringue is golden brown, an additional 8 to 10 minutes. Let stand 1 to 2 hours before cutting.