Cook noodles as package directs. Drain. Set aside. Cook chicken or turkey breast meat at a simmer in water with bouillon cubes, salt, and pepper added until meat is thoroughly cooked. You shoukld have about 1/2 of the water remaining in the pan and it should be a nice broth by now. Cool to lukewarm and chop chicken into large but still bite sized pieces. Return meat to pan with broth.
Return chicken and water to the stove and heat to almost boiling.
Cook onion in butter until tender. Stir in flour to thicken butter and onion mixture. Add this gravy to the chicken and broth, stirring and cooking until thickened. You may need to make more thickening agent to get the desired gravy.
Stir in noodles and frozen peas. Put mixture into a buttered casserole dish and sprinkle cracker crumbs on top. Bake at 350 degrees for 35 minutes.