Preheat oven to 350˚ F. Spray a 9- by 13-inch oven-to-table ceramic baking dish with nonstick cooking spray. Set aside.

Melt the margarine in a large pot over medium heat. Add the onions and sauté for 6-7 minutes, until wilted and beginning to turn golden. Add the spinach and sauté for 3 minutes longer, until most of the liquid is out of the spinach.

Add the flour to make a roux that will thicken the sauce. Stir until the flour is mixed into the other ingredients. Add the sour cream, mayonnaise, salt, and pepper. Stir to combine.

Add the broth, stirring until smooth. Bring to a simmer. The sauce will thicken slightly.

Ladle a layer of spinach sauce into the bottom of the prepared pan. Spread a layer of tightly overlapped parsnips. Top with a layer of sauce. Repeat, alternating parsnips and spinach sauce. There should be a total of 3 layers of sauce and 2 layers of parsnips, with the sauce on the top.

Sprinkle the top with paprika. Bake uncovered for 11⁄2 hours.

Tip

Look for large diameter parsnips, they will slice into larger circles. This will make layering them easier than thinner parsnips which yield smaller circles.