In a medium nonstick skillet, heat 1 tsp. olive oil over medium heat. Saute chopped apple, celery, onion, and a large pinch of kosher salt until translucent, about 10 minutes. Add sausage (casings removed) and rosemary. Continue to cook until sausage is browned, breaking it up into little pieces as it cooks. 

Remove apple-sausage mixture from heat. Transfer to a large bowl and mix with cornbread, parsley and maple syrup. Set aside to cool.

Ensure that a rack is positioned in the center of the oven. Preheat oven to 400F.

While the stuffing is cooling, butterfly turkey breast and flatten to 1/2-inch thickness by placing the butterflied breast between two slices of plastic wrap and pounding with a meat mallet (or if you're like me and don't own one, a rolling pin).

When stuffing has cooled enough to handle, spread on top of turkey breast, leaving a 1/2-inch area around the edges. Start at one side and roll tightly, tying with kitchen twine every 2 inches.

Rub 2 tsp. olive all over turkey. Transfer to a baking sheet or a large roasting pan.

Roast in preheated oven until a thermometer inserted into the thickest part reads 165F, 40-45 minutes. Remove from oven and allow to rest for 15 minutes.

Slice and serve.