Preheat oven to 425°F (218°C). Line a baking sheet with parchment paper.
With a fork, pierce the sweet potatoes all over. Place the potatoes onto the lined baking sheet and place into the preheated oven; bake for 45 minutes or until a knife slides easily into the centre. (While the sweet potatoes are roasting in the oven, skip to the next section and prepare the topping.)
Remove from oven. Cool slightly or until sweet potatoes can be easily handled.
Reduce the oven temperature to 350°F (177°C).
For the topping:
In a medium-sized bowl, whisk the Redpath® Demerara Style Sugar with the minced rosemary, ground cinnamon, salt, and cayenne pepper until well combined.
In a large bowl, toss the chopped pecans with the melted butter. Add the spiced brown sugar mixture to the pecans and stir to coat evenly.
For the casserole:
Grease the bottom and sides of a 9 x 13-inch casserole dish with butter. Set aside.
Slice the slightly cooled sweet potatoes in half lengthwise. Use a large spoon to scoop the insides from the skins into a large bowl; discard skins.
Add melted butter, the Redpath® Golden Yellow Sugar, bourbon, salt, orange zest, ground ginger, black pepper, and nutmeg to the bowl. With a potato masher or a hand mixer, mash the sweet potatoes until the desired consistency is reached.
Spread the mashed sweet potatoes into the greased casserole dish. Evenly top the sweet potatoes with the spiced brown sugar-pecan topping.
Place into the preheated oven and bake until the pecans are caramelized and fragrant and the filling is bubbling around the edges; 35 to 40 minutes.