Bring a large pot of salted water to a rolling boil. Add the cubed sweet potatoes and cook for 12-15 minutes until completely tender when pierced with a fork. Drain thoroughly and return to the pot.

While potatoes cook, combine ground pork, panko, grated onion, garlic, smoked paprika, sage, egg, Worcestershire sauce, salt, and pepper in a large mixing bowl. Mix gently with your hands just until combined. Do not overmix.

Shape mixture into 12 meatballs, about 1.5 oz each. Wet your hands slightly to prevent sticking. Heat 2 tablespoons oil in a 12-inch skillet over medium-high heat. Add meatballs and brown all sides for 6-8 minutes total, turning every 2 minutes. Transfer to a plate.

Add 3 tablespoons butter, heavy cream, cinnamon, and nutmeg to the drained sweet potatoes. Mash until smooth and creamy. Season with salt to taste. Cover and keep warm.

In the same skillet with meatball drippings, carefully pour in bourbon and maple syrup. Scrape up all browned bits from the bottom. Stir in Dijon mustard and chicken stock. Bring to a simmer.

Return meatballs to skillet with any juices. Reduce heat to medium-low and simmer for 8-10 minutes, turning occasionally, until meatballs reach 160°F internally and sauce reduces by one-third.

Remove skillet from heat. Add cold butter pieces and whisk constantly until butter melts into sauce, creating a glossy finish. Season with salt and pepper.

Divide sweet potato mash among four plates. Top each with 3 meatballs and spoon bourbon-maple sauce over everything. Serve immediately.