Heat your oven to 400 degrees F. Peel your onion and finely chop it. (You will end up with about 2 cups of chopped onion; don't use any more than that.)
In a 5-quart pot, heat your olive oil on medium-high. Add the chopped onion and give it a stir to coat it with the oil. Let the onion cook for about five minutes, or until tender.
Stir in your rice until it's combined. Then, stir in your spinach, stock, salt and pepper. Cover the pot and bring it to a simmer. When it starts to simmer, uncover the pot and cook the mixture for seven minutes.
While the pot is simmering, grate your Parmesan, if needed. (I throw chunks of cheese in my blender.) After the pot has simmered for seven minutes, stir in 1/2 cup of your Parmesan.
Transfer the rice mixture to a glass 9x13 pan. Cover the pan with foil and bake it for 15 minutes.
While the risotto is baking, rinse your asparagus and cut off the tough bottoms (cut off and discard the bottom two inches.) Cut the remaining stalks into 1-inch pieces.
After the risotto has baked for 15 minutes, stir in your asparagus pieces. Sprinkle your remaining 1/2 cup of Parmesan over the top. Cover the pan again and bake it an additional 20 minutes, or until the liquid is absorbed.
Serve the risotto with red pepper flakes, additional Parmesan, and extra salt, if needed. Store leftovers in the refrigerator for up to four days, or freeze them. The risotto reheats well in the microwave.
Adapted from Cooking Light. I used stock instead of broth for more flavor, omitted the nutmeg, added pepper and doubled the recipe to make it in a 9x13. If you want to make half of this recipe, you can use a Dutch oven from start to finish. The 9x13 recipe serves 12 as a side dish or 8 as an entrée.