Preheat the oven to 375 degrees F.
To bread the chicken, blend the flour, salt and pepper in a small bowl. Then dust the chicken on both sides with the seasoned flour, coating well. In a saute pan over medium-high heat, add the grapeseed oil and allow to heat. Then add the floured chicken, skin-side down, cooking until slightly browned. This will take 4 to 5 minutes, then flip and repeat the process on the bottom side, again for 4 to 5 minutes. Once browned, finish the chicken in the oven until the internal temperature reaches 160 to 165 degrees F, about 6 minutes. Once cooked, remove from the oven, keep the chicken warm on a covered plate and discard any excess oil from the pan.
Return the pan to medium heat, splash or deglaze with the wine, allowing to dissipate. Next, add the onions, stir and cook until the onions are slightly translucent, 3 to 4 minutes. Next, add the lemon juice and garlic, stir again and cook until warmed. Finally, remove from the heat, stir in the parsley and butter to finish the sauce. Serve over the chicken.