Step 1

Preheat the oven to 425 degrees Fahrenheit. Line a large, rimmed baking sheet with parchment paper to catch the sweet potato drippings. Grease a 9-inch square baker (or any other 2-quart baker) with butter or cooking spray. Remember to leave the butter at room temperature so it has time to soften.

Step 2

To prepare the filling: Prick each sweet potato with a fork about 5 times so steam can escape. Place the whole sweet potatoes on the prepared baking sheet and bake until they yield easily to a gentle squeeze (use oven mitts!), somewhere between 45 minutes to 1 hour 15 minutes, depending on their size. Set them aside to cool for a few minutes.

Step 3

Reduce the oven temperature to 350 degrees. Once the potatoes are cool enough to safely handle, slice each one in half. Use a big spoon to scoop the insides into a large mixing bowl, then discard the skins.

Step 4

Add the melted butter, milk, maple syrup, vanilla, nutmeg and salt to the bowl. Use a hand mixer to whip the ingredients together until they’re smooth and creamy (alternately, use a potato masher or stir by hand). Scoop the mixture into the prepared baker and spread it in an even layer.

Step 5

To prepare the topping: In a medium bowl, combine the softened butter (if it’s not soft enough to stir yet, microwave it in 6 to 8 second intervals), sugar, pecans, optional rosemary, cinnamon and salt. Stir until the mixture is evenly incorporated. Dollop small forkfuls evenly all over the sweet potato filling.

Step 6

Bake for 30 minutes, until the pecans are golden and fragrant, and the filling is sizzling around the edges and warmed all the way through. Serve.