Creamy Tuscan Chicken

Name: Creamy Tuscan Chicken
Ingredients: 4 chicken cutlets (about 1 1/2 pounds total); 3/4 teaspoon kosher salt , divided; 1/4 teaspoon freshly ground black pepper; 1 tablespoon dried oregano; 3 tablespoons olive oil , divided; 1 medium shallot , minced; 1/3 cup sun-dried tomatoes (drained and patted dry if oil-packed); 4 cloves garlic , minced; 1/2 cup dry white wine; 1 cup heavy cream or half-and-half; 1 ounce finely grated Parmesan cheese (about 1/2 firmly packed cup grated on a Microplane or 1/3 cup store-bought); 5 ounces baby spinach (about 5 packed cups)