Preheat the oven to 425. Have ready a roasting pan.
Peel and slice the sweet potatoes into 1 inch thick slices, and scatter them on the roasting pan, not touching.
Melt the butter, and drizzle it on top of the sweet potatoes. Sprinkle on the salt. Toss to coat, and then redistribute on the pan in a single layer, not touching.
Roast for 20 minutes.
Flip with tongs, and roast for another 20 minutes.
The potatoes are done when they are golden brown and crisp, and the insides are light and fluffy.
To make the maple pecan sauce: heat the pecans in a pan just until fragrant 1 or two minutes.
Bring the maple syrup to a boil in a small sauce pan.
Add the pecans.
Wait for the sauce to come back to a boil, cook for 1 minute, and then remove from heat.
Pour the sauce over the sweet potatoes and serve.
