Preheat oven to 425°F.
Line a cookie sheet with aluminum foil.
Peel and cut sweet potatoes into 1 inch sized chunks.
Place sweet potato chunks in a large bowl and season generously with salt and pepper. Set aside.
Zest and juice one lemon, set aside.
In a small sauce pan heat, butter, olive oil and honey over medium heat until it foams up.
Turn off heat and stir in reserved lemon juice, lemon zest, cinnamon and freshly grated nutmeg.
Pour hot glaze over sweet potatoes in the bowl and toss to coat.
Spread sweet potato chunks and glaze onto foil lined cookie sheet, in a single layer.
Bake for 15 minutes.
Toss chunks about half way through cook time to ensure they brown evenly on all sides.
Sweet potatoes are done once glaze has thickendd and caramelized, the chunks start to brown nicely along the edges, and they are soft when pierced with a fork.
To serve, top with a tablespoon of finely diced preserved lemon peel if desired.