Preheat oven to 350 degrees celsius. Heat half of oil and butter in skillet. Season chicken with half of salt, pepper and add to pan when oil and butter are bubbly

Sear chicken breast over medium high heat until golden brown, 1 minute per side and remove to a baking dish.

Add remaining oil and butter to skillet and stir in shalots/onions and cook until caramelized (4 minutes). Add blueberries and cook 1 minute. Stir in vinegar, maple syrup, rosemary, and remaining salt and pepper; then simmer for 10 minuted or until blueberries collapse.

Pour bluebery balsamic over chicken and put in baking dish in oven for 30 minutes until chicken is cooked through to 165 celsius.