Mashed Sweet Potato Casserole with Bourbon

I tried this out for the first time this Thanksgiving and it was a huge success.  This makes me a sweet potato fan.  

Ingredients

6 pounds medium Garnet sweet potatoes

3/4 cup packed dark brown sugar

3/4 cup all-purpose flour

1 teaspoon kosher salt

7 tablespoons cold unsalted butter, cut into 14 pieces

1 1/2 cups pecan halves, finely chopped (about 6 ounces)

1/4 cup plus 2 tablespoons bourbon

6 tablespoons unsalted butter (3/4 stick), plus more for coating the dish

2 teaspoons finely grated orange zest (from 1 medium orange) 

1 1/2 teaspoons kosher salt 

3/4 teaspoon ground cinnamon

3/4 teaspoon freshly grated nutmeg

1/4 cup whole milk

Heat the oven to 375°F and arrange a rack in the middle. Place the sweet potatoes on a foil-lined baking sheet and roast until very soft to the touch, about 45 minutes to 1 hour. Meanwhile, prepare the topping.

Whisk the sugar, flour, and salt in a medium bowl until combined. Add the butter and, using a pastry blender or your fingers, cut it into the flour mixture until the butter’s in pea-size pieces or smaller, about 5 minutes. Add the pecans and toss with your fingers to combine.

Squeeze clumps of the mixture between your fingers to form irregularly shaped pieces about the size of kidney beans. Cover and place in the refrigerator until ready to use.

When the sweet potatoes are done roasting, place the baking sheet on a wire rack and set it aside until the sweet potatoes are cool enough to handle, about 20 minutes. Meanwhile, place the bourbon, butter, orange zest, salt, cinnamon, and nutmeg in a small saucepan over medium heat and cook, stirring occasionally, until the butter has melted and the mixture has started to bubble, about 5 minutes; set aside.

Coat a 13-by 9-inch baking dish with butter and set it aside.

When the sweet potatoes are cooled, cut them in half lengthwise. Scrape the flesh out with a spoon and transfer it to a large bowl; discard the skins. Using a potato masher, mash the flesh until it’s almost smooth but some chunks remain. Add the bourbon mixture and the milk and stir until evenly combined. Transfer the mixture to the prepared baking dish.

Evenly sprinkle the streusel topping over the sweet potatoes. Bake until the streusel is golden brown, about 20 minutes. Place the dish on a wire rack and let it sit 10 minutes before serving.