1. Pat chicken dry with paper towels and season with salt and pepper. Toast 6 tablespoons flour in Dutch oven over medium heat, stirring constantly, until just beginning to brown, about 5 minutes. Transfer flour to medium bowl and wipe out pot. Heat 1 tablespoon oil in now-empty Dutch oven over medium-high heat until just smoking. Cook chicken until well browned all over, about 10 minutes; transfer to plate. When chicken is cool enough to handle, remove and discard skin. Pour fat (you should have about 2 tablespoons) into another small bowl; reserve.
2. Add onion and 1 tablespoon oil to now-empty pot and cook over medium heat until softened, about 5 minutes. Stir in thyme and cook until fragrant, about 30 seconds. Add 7 cups broth, chicken, and bay leaves and bring to boil. Reduce heat to low and simmer, covered, until white meat registers 160 degrees and dark meat registers 175 degrees, 20 to 25 minutes. Remove from heat. Transfer chicken to clean plate. When chicken is cool enough to handle, shred into bite-size pieces, discarding bones.
3. Meanwhile, combine remaining chicken broth, reserved fat, and remaining oil in liquid measuring cup. Process remaining flour and ½ teaspoon salt in food processor until combined. With machine running, slowly pour in broth mixture and process until mixture resembles coarse meal. Turn dough onto lightly floured surface and knead until smooth. Divide in half.
4. After kneading the dough briefly, roll each dough half into a 10-inch square of 1/8 inch thickness. Using a sharp knife or pizza wheel, cut the dough into 5 by 1-inch rectangles. Place handful of noodles in single layer on parchment-lined plate, cover with another sheet of parchment, and repeat stacking with remaining noodles and additional parchment, ending with parchment. Freeze until firm, at least 10 minutes or up to 30 minutes.
5. Return broth to simmer and add noodles. Cook until noodles are nearly tender, 12 to 15 minutes, stirring occasionally to separate. Remove 1 cup broth from pot and whisk into reserved toasted flour. Stir broth-flour mixture into pot, being careful not to break up noodles, and simmer until slightly thickened, 3 to 5 minutes. Add shredded chicken and parsley and cook until heated through, about 1 minute. Season with salt and pepper. Serve.
MAKE AHEAD Broth and chicken can be made through step 2 and refrigerated in separate airtight containers for 2 days. Dough can be made through step 3, wrapped in plastic wrap, and refrigerated for 1 day. To finish, proceed with step 4.