Working in batches, add chicken to the skillet in a single layer and cook until golden brown and cooked through, reaching an internal temperature of 165 degrees F, about 4-5 minutes per side; set aside. Reduce heat to medium low.
Add garlic and shallot, and cook, stirring frequently, until fragrant, about 2 minutes; season with salt and pepper, to taste.
Whisk in remaining 1 1/2 tablespoons flour until lightly browned, about 1 minute.
Gradually whisk in chicken stock, half and half and sun dried tomatoes. Bring to a boil; reduce heat and simmer, stirring occasionally, until reduced and slightly thickened, about 3 minutes. Stir in spinach, Parmesan and parsley; season with salt and pepper, to taste. Return chicken to the skillet.