Preheat oven to 180C/350F.

Whisk together the Italian Dressing ingredients in a bowl. It will be thicker than salad dressing.

Cut a pocket into each chicken breast, taking care not to cut all the way though.

Coat the chicken (inside and out) with the Italian Dressing.

Place chicken on work surface. Stuff with sun dried tomato, top with cheese then finish with spinach leaves. Just stuff in as much as you can.

Seal with toothpicks (just stick them in on the diagonal - see photo in post).

Heat oil in an ovenproof skillet over high heat. Add chicken and cook for 1 1/2 minutes on each side, or until golden.

Transfer to oven and cook for 15 minutes, or until cheese is melted and bubbly and chicken is cooked through. Rest for 3 minutes before serving, drizzled with the juices in the skillet.