Chicken Breast Stuffed with Italian Sausage

Ingredients

• 2 bunches fresh baby spinach (stems removed and washed in 2 or 3 changes of cold water)
• 1 small yellow onion (chopped fine)
• 2 cloves garlic (chopped fine)
• ¼ cup extra virgin olive oil
• ¾ pound Italian sausage(removed from casing)
• ½ cup grated Parmigiano-Reggiano
• 1 egg
• Kosher salt and fresh ground black pepper to taste
• 8 chicken breast halves (skin, bones and cartilage removed)