Preheat oven to 400°F (200°C).

In a small mixing bowl, whisk together the garlic powder, smoked paprika, Italian seasoning, salt, and black pepper.

Using a sharp knife, cut a horizontal pocket into the thickest part of each chicken breast, taking care not to slice completely through the other side.

Evenly coat the interior and exterior of the chicken breasts with the prepared seasoning rub.

Stuff each pocket with one slice of mozzarella cheese and three trimmed asparagus spears. Secure the openings with 2-3 toothpicks per breast.

Heat the olive oil and butter in a large oven-safe skillet over medium-high heat until the butter is foamy.

Place the stuffed chicken breasts in the skillet and sear for 4 minutes per side, or until a golden-brown crust has formed.

Transfer the skillet directly into the oven and bake for 12 to 15 minutes, until the internal temperature of the chicken reaches 165°F (74°C).

Remove from the oven and allow the chicken to rest for 5 minutes. Carefully remove the toothpicks before serving.