Step 1

Heat oven to 350 degrees. Grease a 9-by-13-inch baking pan; set aside.

Step 2

For crust: Mix 1-3/4 cups flour and the powdered sugar in a medium mixing bowl. Cut in the butter with a pastry blender until mixture resembles coarse crumbs. Press mixture evenly into the prepared baking pan. Bake until golden, about 10-12 minutes.

Step 3

For filling: Mix the 1-1/2 cups sugar, flour, and salt in a large bowl. Lightly beat egg yolks and stir into the sugar mixture along with the cream. Stir in the rhubarb, strawberries, and lemon juice. Spread mixture evenly over crust. Bake until firm, about 1 hour.

Step 4

Beat egg whites in large mixer bowl until foamy. Beat in ½ cup sugar one Tablespoon at time until stiff peaks form. Spread over the rhubarb mixture in pan. Bake until light brown, 10-15 minutes. Cool in pan on wire rack. Cut into squares. Makes 8-10 servings.