Measure the olive oil, honey and chili powder into a medium mixing bowl and mix.
Add the diced sweet potatoes and stir well to coat with the oil and seasonings.
Heat a large skillet over medium high and add the sweet potatoes. Spread them into a single layer if possible.
Put the spinach leaves into the same bowl and rub around to pick up any leftover oil, honey and spices and set aside.
After the sweet potatoes have taken on a little color, turn the heat down to medium and cover the skillet with a lid. Stir occasionally and cook until the sweet potatoes are finished to your liking, 10 minutes or longer. Remove from the heat.
Add the spinach leaves to the skillet and put the lid back on until it has wilted.
If roasting in the oven or on the grill, carefully add the hot sweet potatoes to the bowl with the spinach and gently stir to distribute the spinach. Cover to allow the heat from the sweet potatoes to wilt the spinach.
Before serving, add salt and pepper to taste.