Mix egg yolks and lemon juice with cold water. Mix 2 cups flour, 1/2 teaspoon salt, shortening, and egg yolk mixture like pie crust. Press 1/2 of crust dough in the bottom of a 13"x9"x2" baking pan. Roll out remaining dough for top crust and set aside.
Combine apples, sugar, 1 tbsp. flour, cinnamon, and 1/4 tsp. salt; spread evenly over crust in pan. Dot with butter pats. Cover with remaining crust dough and seal edges.
Bake at 350 degrees for 30 - 40 minutes. Let cool. Then combine frosting ingredients and spread or drizzle over top.