1. Combine first 8 ingredients in a large Dutch oven. Bring to a boil, stirring to dissolve sugar and salt. Cool completely. Add turkey to brine; cover and chill 4 hours.
2. Remove turkey from brine; discard brine. Rinse turkey; pat dry. Loosen skin from breast by inserting fingers, gently pushing between skin and meat. Rub 1/2 teaspoon ground pepper under loosened skin. Place on a roasting pan coated with cooking spray.
3. Preheat oven to 400°.
4. Bake turkey at 400° for 45 minutes or until a thermometer registers 160°. Remove from oven; cover loosely with foil. Let stand 15 minutes. Remove skin, and discard.
5. Heat oil in a large nonstick skillet over medium-high heat. Add shallots; sauté 1 minute. Add mushrooms; sauté 6 minutes or until lightly browned. Add broth; bring to a boil, and cook until reduced to 2 cups (about 20 minutes). Combine flour and 2 tablespoons water in a small bowl; stir with a whisk. Stir flour mixture into mushroom mixture; simmer 3 minutes or until slightly thickened, stirring frequently with a whisk. Remove from heat; stir in butter, 1 tablespoon at a time. Stir in parsley and remaining 1/2 teaspoon ground pepper. Serve gravy with sliced turkey breast.