Step 1

Preheat oven to 400°. In small bowl, combine the spinach, sun-dried tomatoes, goat cheese, garlic, 1/4 teaspoon pepper and 1/8 teaspoon salt.

Step 2

Cut a pocket horizontally in the thickest part of each chicken breast. Fill with spinach mixture; secure with toothpicks.

Step 3

In an 8-in. cast-iron or ovenproof skillet, heat 1-1/2 teaspoons oil over medium heat. Brown chicken on each side. Place in oven; bake 10 minutes.

Step 4

Meanwhile, toss asparagus with remaining 1-1/2 teaspoons oil, 1/4 teaspoon pepper and 1/8 teaspoon salt; add to skillet in oven. Bake until a thermometer inserted in chicken reads 165° and asparagus is tender, 10-15 minutes longer. If desired, drizzle with vinegar. Discard toothpicks before serving.