Combine water and cornmeal in a medium saucepan; stir well. Bring to a boil. Cook 1 minute; stir frequently. Remove from heat; stir in milk and next 7 ingredients (milk through pimento). Set cornmeal mixture aside.
Beat egg whites at high speed of a mixer until foamy. Add sugar, beating until stiff peaks form. Gently stir one-fourth of egg white mixture into cornmeal mixture; gently fold in remaining egg white mixture. Fold in Roasted Summer Squash.
Spoon mixture into a 1 1/2-quart casserole dish coated with cooking spray. Bake at 375° for 50 minutes or until set.
Note: Prepare the Roasted Summer Squash before preparing the rest of the recipe.