For the sweet potato mash: Put the sweet potatoes in a saucepan with enough water to cover. Bring to a boil over medium-high heat and simmer until tender, about 15 minutes. Drain and mash with a masher or fork. Mix in the butter and season with salt and pepper. Keep warm until serving.
For the sauteed kale: Heat a saute pan to medium heat. Add the bacon to the pan and cook until the fat is rendered and the bacon is almost crisp. Add the garlic and onions and sweat until the vegetables are transparent. Add the kale and saute until wilted, about 3 minutes. Season with salt and pepper. Reserve
For the chicken breasts: Heat a large saute pan to medium heat. Sprinkle the chicken breasts with salt and pepper. Add the grapeseed oil to the pan, followed by the chicken. Cook until the breasts are cooked through, about 4 minutes on each side. Transfer to a plate to rest and top with the butter, letting it melt over the chicken. Reserve.
For the red wine feta sauce: Put the wine in a small saucepan and cook until reduced by almost half. Add the demi-glace and reduce until the sauce coats the back of a spoon. Remove from the heat and whisk in the melted butter from the chicken plate. Fold in the feta and season with salt and pepper.
To serve: Spoon some sweet potato mash in the center of each plate, making a well in the middle. Spoon some kale in the well of the sweet potato mash. Top with a chicken breast and spoon on some of the red wine feta sauce. Enjoy!