Heat the oven to 375 degrees F.
Butterfly the chicken breast pieces by cutting across the breast but not all the way through. Open the breasts up and pound lightly between parchment paper. Peel paper away and season the meat with salt and pepper.
Cover the seasoned chicken cutlets with blue cheese crumbles, pecans and scallions in equal amounts. Roll the chicken, wrap each roll with bacon and secure with toothpicks. Season the outside of the rolls with salt and pepper.
Heat the olive oil in skillet over medium-high heat. Brown the chicken evenly all over, 5 to 6 minutes. Transfer the chicken to a small baking sheet, place in the oven and cook 10 minutes more.
Melt the butter in the same skillet pan the chicken was seared in over medium heat. Whisk in flour, cook 1 minute then whisk in stock. Let thicken a minute then whisk in the half-and-half and grain mustard, season with salt and pepper, reduce heat to warm.
Halve the chicken and stack to show off the center. Set chicken in gravy or pour over top. Serve with rice and greens, if desired.