Preheat the oven to 375°F. Line a large baking sheet with parchment paper.
In a large bowl, combine the ground pork, rolled oats, grated apple, chopped sage, diced onion, minced garlic, egg, salt, and black pepper. Mix with your hands until just combined.
Shape the mixture into a loaf about 8 inches long and place it in the center of the baking sheet.
In a separate bowl, toss the carrots, parsnips, and potatoes with the olive oil and dried rosemary until evenly coated.
Arrange the vegetables around the meatloaf on the baking sheet in a single layer.
Bake for 50 to 55 minutes, until the meatloaf reaches an internal temperature of 160°F and the vegetables are tender when pierced with a fork.
Remove from the oven and let the meatloaf rest for 5 minutes before slicing.