Begin the polenta recipe as you start to make the guinea hens.
Preheat an oven to 375 degrees.
Heat a saute pan over medium heat. Add the bacon cubes and cook until evenly browned. Remove the bacon and reserve on paper towels, leaving the bacon fat in the skillet. Saute the pearl onions in the fat over moderate heat for about 3 minutes, until they begin to caramelize. Being careful not to let them burn, reduce the heat and continue to saute another 4 to 5 minutes, or until the onions begin to soften. Remove the onions and reserve.
Season the guinea hen breasts with salt and pepper and saute in the skillet that the bacon and onions had been browned in, adding some olive oil if necessary. Cook over mediumhigh heat until brown on both sides, about 6 to 8 minutes total. Remove the hen from the pan, place in a small roasting pan and into the oven for 8 to10 minutes to continue cooking while the remainder of the dish is finished.
Pour off any excess fat from the saute pan and add the mushrooms. Cook the chanterelles for 3 to 4 minutes, return the onions to the pan, add the bacon and saute for a moment to combine. Add the wine and allow to reduce for 1 minute.
Add the stock to the pan and bring to a boil. Reduce the heat to a simmer, return the hens to the pan to braise for a few minutes with the mushrooms, onions and bacon.
When the liquid has reduced by half and the hens are sufficiently cooked (test by piercing the flesh with a knife to see if the juices run clear) add the butter and swirl in to combine. Add the tarragon and serve on a bed of herbed polenta.
Note: roast game or chicken stock is made by using game bird or chicken bones that have
been roasted in an oven, (along with the appropriate stock vegetables) until richly browned,
before a standard stock making recipe is followed.