In a wide sauté pan, over high heat, drizzle some olive oil. Add the chicken filets and sear for 2 minutes until lightly coloured. add the onions, garlic and bread croutons pieces.
Spoon the butter and let it melt and colour the bread and chicken pieces for 2 minutes or so.
Next, add the cherry tomatoes, pesto and a few basil leaves and spring onions.
Sauté for a further minute or so. Add the white wine and balsamic vinegar to help create a dressing.
Remove from the heat and toss in the spinach to wilt slightly.
In the meantime, prepare the salad. In a serving bowl, add the salad leaves and toss with oil, vinegar and extra pesto until lightly coated.
Add the chicken mixture to the salad and serve while warm.