Rinse Cornish game hens with cold water and pat dry with paper towels. Split hens in half by cutting down backbone and then through breastbone. Mix sage, rosemary, garlic powder, salt, and pepper; rub hens inside and out. Wash hands.
In 5-quart Dutch oven, melt butter. Over medium-high heat, brown hens on all sides. Add wine, cover and simmer until tender (approximately 45 minutes). Insert an instant-read thermometer into the thickest part of the chicken. Internal temperature should read 180 degrees F.
Remove hens to serving platter, cover and keep warm. Mix flour with 1/2 cup warm water and add to pan juices for Cornish sauce.
Serve with noodles mixed with sour cream and Parmesan cheese.