Polenta Florentine

Ingredients

• cooking spray or butter, for coating the baking dish
• 1 (18-ounce) tube prepared polenta, cut into 1/4-inch-thick rounds
• Freshly ground black pepper
• Between 8 and 12 oz. baby spinach
• 2 tablespoons unsalted butter
• 1/2 medium yellow onion, diced
  
• 1 clove garlic, minced
• 1/2 teaspoon kosher salt, plus more for seasoning
• 2 tablespoons all-purpose flour or cornstarch
• 2 cups whole milk
• Generous 1/2 cup grated Parmesan cheese, divided**
• 2 teaspoons freshly squeezed lemon juice

Directions

Arrange a rack in the middle of the oven and heat to 400°F. Coat either a 7×11-inch baking dish or a 9×9-inch baking dish with cooking spray or butter. Season the tops of the polenta rounds lightly with salt and pepper. Place the rounds in the baking dish in 3 rows (or more, depending upon which baking dish you use), overlapping them slightly; set aside.

Heat a large frying pan over medium heat. Add the spinach and toss until completely wilted, 3 to 4 minutes. Transfer to a strainer set over a medium bowl. Press most of the water out of the spinach. If the baby spinach leaves were large, sometimes I take kitchen shears and cut the spinach into smaller pieces, once it has been drained. This makes it easier to mix into the sauce.

Melt the butter in the same pan over medium heat. Add the onion, garlic, and 1/2 teaspoon salt. Cook until softened, about 5 minutes. Add the flour or cornstarch and cook, stirring constantly, for 1 minute. Add the milk and bring to a simmer, stirring frequently with a wooden spoon. Continue simmering, stirring constantly, until thickened to the consistency of heavy cream, about 2 minutes more.

Remove from the heat and stir in 1/4 cup of the cheese (or up to 1/2 cup, if you really like Parmesan), reserved spinach, and lemon juice. Taste and season with salt and pepper as needed.

Pour the spinach mixture evenly over the polenta. Sprinkle with the remaining 1/4 cup (or more) of cheese. Bake uncovered until bubbling around the edges and golden-brown, about 25 minutes. If the top of the dish hasn’t turned brown, you can turn the oven to broil and broil until the surface is golden-brown in spots, 3 to 5 minutes. Let cool 10 minutes before serving.