Cook pasta according to package directions. Drain thoroughly, return to pot and over .

Meanwhile, heat 2 teaspoons of oil in a large skillet over medium-high heat. Add chicken and cook, stirring once or twice, until browned, 4 to 6 mins.:set aside.

Add remaining oil and onion, fennel, garlic, salt and thyme to skillet and reduce heat to medium. Cook,stirring often, until vegetables begin to soften, 5 to 7 mins. Add sherry and cook, stirring often, until evaporated, 1 to 2 mins. Sprinkle with flour and stir to coat. Add broth and milk, increase heat to medium high and bring to a simmer, stirring constantly. Cook, stirring often, until sauce is thickened, 2 to 3 mins.

Add chicken and any accumulated juices back to skillet and cook, stirring often, until chicken is cooked through, about 3 mins.

Add spinach and cook until wilted, 30 to 90 secs. Remove from heat and stir in Parmesan and chives. Stir chicken and sauce into pasta. Season with black pepper.