Preheat the oven to 375 degrees F.
Prepare the hens: In a mini food processor, pulse the garlic and 1 teaspoon salt to a paste. Using your fingers, make a pocket between the flesh and the skin of each Cornish hen. Stuff half the garlic paste between the skin and the flesh of the hens, evenly covering by pushing the paste along the flesh from the outside. Rub both hens all over with olive oil and sprinkle with salt and a grind of pepper. Cross the legs of each hen and tie together with kitchen string. Set aside and allow to come to room temperature for about an hour.
In a baking dish large enough to hold both hens, mix together the remaining garlic paste, the bell pepper, onions, cayenne pepper, paprika, a pinch of salt and a grind or 2 of pepper.
Place the prepared hens on top of the vegetables in the pan and slowly pour in 2 cups chicken stock. Place in the oven and cook until the temperature reaches 160 degrees F between the leg and the body of the hen when tested with an instant-read thermometer, about 40 minutes.
Remove the hens from oven and remove from the pan to a plate. Cover lightly with aluminum foil to keep them warm while making the gravy. In a medium saute pan, melt the butter over medium heat. Add the vegetables from the baking dish and the flour. Whisk the flour briskly until it is combined with all the pan contents. Add the wine and let reduce. Take a sip of wine for yourself; you've worked hard. Stir in the remaining 1 cup chicken stock. Taste and season with salt and pepper, and then cook until the sauce has thickened to a gravy consistency, about 5 more minutes. To serve, remove the aluminum foil from the hens. Remove the string and cut in the birds in half. Pour the gravy over the top and garnish with chopped parsley.