Preheat oven to 400ºF.
Lightly spray twelve medium non-stick muffin pan cups with cooking spray.
Heat oil in large skillet over medium-low heat; add onions, peppers and celery, and cook, stirring occasionally, 2-3 minutes, or until softened. Stir in pears, lemon juice, salt and poultry seasoning, and cook 1 minute. Add bread and remove from heat.
Combine egg and chicken stock in bowl. Pour over bread mixture and stir.
Gently press stuffing into muffin pan. Bake 30 minutes. Remove from heat and let stand 5 minutes. Run plastic knife gently around edge of each muffin before removing.
While stuffing bakes, arrange chicken on 13x9-inch parchment-lined baking sheet. Poke breasts on both sides 6-7 times with fork and brush both sides with vinaigrette. Bake 25 minutes, or until internal temperature is 165ºF.
Combine juice and 1/2 cup water in medium saucepan over medium heat; add sugar and stir to dissolve. Add cranberries and cook, stirring continuously, 10 minutes, or until cranberries pop. Add pineapple and remove from heat.
Top chicken with cranberry sauce.