Preheat the oven to 400 degrees F. Prick the sweet potatoes all over with a fork, rub with olive oil, and sprinkle generously with salt and black pepper. Place on a rimmed foil-lined baking sheet and bake until tender and easily pierced with a fork, 45 to 50 minutes. Let cool slightly. Meanwhile, melt the butter in a small skillet over medium heat until lightly browned. Stir in the coriander and cinnamon and cook until fragrant, 2 minutes. Remove from the heat and set aside. When the potatoes are cool enough to handle, slice 1/4 inch off the tops of each one, discarding the skin. Scoop out the flesh, leaving a 1/4-inch border inside the potato, and place the flesh in a large bowl. Add the browned butter and spices, cream and orange juice, season with 1/2 teaspoon salt and 1/4 teaspoon black pepper, and beat using a hand mixer until well combined and fluffy, 3 minutes. Replace the foil on the baking sheet. Spoon equal amounts of the whipped potatoes back into each potato shell. Bake until the filling is browned and the potatoes start to brown around the edges, 15 minutes. Top with broken Sweet and Spicy Walnuts.
Preheat the oven to 325 degrees F. Line a rimmed baking sheet with parchment paper and spray with cooking spray. Whisk together the maple syrup, brown sugar, salt, black pepper, cayenne and orange zest. Toss in the walnuts to coat, and then spread in an even layer on the baking sheet. Bake until crisp and lightly browned, 20 minutes, stirring halfway through baking time. Let cool completely.