Wash the sweet potatoes thoroughly and pat dry. Place each potato on a cutting board and make thin slices (about 0.125 inches apart) along the length of each potato, stopping just before you reach the bottom.
Drizzle each Hasselback sweet potato with olive oil, ensuring it seeps into the slices. Season with salt and pepper to taste.
Place the sweet potatoes on a baking sheet lined with parchment paper. Bake for 35-40 minutes, or until they are tender and slightly crispy on the edges.
While the sweet potatoes are baking, combine the cheddar cheese, cream cheese, sour cream, green onions, minced garlic, smoked paprika, salt, and pepper in a bowl. Mix until thoroughly combined.
Once the potatoes are soft, remove them from the oven. Carefully widen the slits in the sweet potatoes a bit more and stuff each slit with the cheesy mixture, packing it generously.
Return the stuffed sweet potatoes to the oven and bake for an additional 10-15 minutes, or until the cheese is bubbly and golden brown.
Remove from the oven and let cool for a minute. Garnish with fresh parsley and additional chopped green onions, if desired. Serve hot.