1/2 cup heavy cream
1/2 cup chicken or vegetable broth
1 tablespoon pureed chipotle in adobo sauce
Coarse or kosher salt and freshly ground pepper to taste
2 large sweet potatoes, very thinly sliced
Lime wedges to serve
3 cups cooked orzo (preferably whole-wheat)
2 cups diced fresh tomatoes
1 (15.5 ounce) can black beans, rinsed and drained
2 cups shredded or slivered provolone cheese, divided
6 scallions, white and green parts, trimmed and minced, divided
1/4 cup sour cream, plus more to serve if desired
Preheat the oven to 400°F. Lightly oil a shallow 2-quart baking dish or spray with nonstick cooking spray.
In a large bowl, combine the cooked orzo, tomatoes, black beans, 1 cup provolone, and half the scallions.
In a small bowl whisk together the sour cream, heavy cream, broth, pureed chipotles, and salt and pepper.
Add the sour cream mixture to the orzo mixture and mix well.
Place half of the orzo mixture in the prepared pan, layer over half the sliced sweet potatoes -- barely overlapping the edges of the slices -- and repeat using the rest of the orzo mixture and the rest of the sweet potatoes
Sprinkle the remaining provolone over the casserole, cover with foil and put in the oven.
Bake for 20 minutes, then remove the foil. Continue to bake for a total of 50 to 60 minutes, until browned and bubbly, and until a knife inserted in the casserole slides in easily through the potatoes.
Remove from the oven, let sit for 5 minutes, sprinkle the rest of the scallions on top, and serve hot.
Serve with lime wedges and pass the additional sour cream, if desired.