Reserve 1 cup of juice and mix in cornstarch. In a large stock pot, mix sugar with cherries and remaining juices and cook until bubbling, stirring constantly. Add the reserved juice/cornstarch mixture and stir to combine. Cook for about 3 minutes until thickened.
Preheat oven to 400 degrees F. Coat a smooth surface in flour and roll out 2 rounds of pie crust lengthwise. Line the bottom of a 9x13 baking pan with dough. Trim the excess and pinch the edges of the pie crust. Fill the crust with filling. Cut 6 1-inch strips of pie crust. Use small square cookie cutter to cut out 9 squares. Twist the strips and arrange across the pie to create ribs. Place the squares down the center of the ribcage. Brush crust with egg. Bake 35-45 minutes until the crust is golden brown and juices begin to bubble.