Puglia's rice casserole with clams is ultra cozy and creamy.

Ingreadients:

• 3 tablespoons extra-virgin olive oil, divided
• 1 medium-size yellow onion, cut into 1/4-inch-thick slices (about 2 cups)
• 3 medium garlic cloves, finely chopped (about 1 tablespoon) 
• 1/2 teaspoon crushed red pepper
• 1 1/2 teaspoons kosher salt, divided
• 1/2 cup (4 ounces) dry white wine
• 2 pounds littleneck clams (about 24 clams), soaked 
• 1/2 cup cold water
• 4 small Yukon Gold potatoes (about 10 ounces), scrubbed and thinly sliced (about 2 cups), divided
• 12 ounces cherry tomatoes (about 2 1/2 cups), halved, divided
• 1 ounce pecorino Romano cheese, finely shredded (about 1/4 cup), divided
• 1 ounce Parmigiano-Reggiano cheese, finely shredded (about 1/4 cup), divided
• 1 cup uncooked arborio rice, divided
• 2 1/2 to 3 cups fish broth (such as Aneto), as needed
• Finely chopped fresh flat-leaf parsley, for garnish

Direction

1. Preheat oven to 325°F with rack positioned 6 inches from heat. Heat 2 tablespoons oil in a 12-inch high-sided broiler-safe skillet or enameled cast-iron skillet over medium-high. Add onion, garlic, crushed red pepper, and 1/2 teaspoon salt; cook, stirring occasionally, until onion is slightly softened, about 3 minutes. Add wine; cook, stirring constantly, until liquid is slightly reduced, about 2 minutes.
2. Add soaked and drained clams and 1/2 cup cold water to skillet; reduce heat to medium. Cover and cook until clams have opened, about 12 minutes, checking clams every minute after 5 minutes of cooking. As clams open, transfer each to a large plate, and re-cover skillet. After 12 minutes, remove skillet from heat; remove and discard any unopened clams. Separate each clam shell, discarding empty shell halves and reserving halves with clams attached; set aside. Strain remaining mixture in skillet over a medium-size heatproof bowl, reserving cooking liquid in bowl and solids separately. Do not wipe skillet clean.
3. Spread half of the reserved strained onion mixture (about 3/4 cup) evenly in skillet. Arrange half of the sliced potatoes (about 1 cup) evenly over onion mixture; sprinkle with 1/2 teaspoon salt. Scatter half of the tomatoes (about 1 cup) over potatoes; sprinkle evenly with 1 1/2 tablespoons pecorino Romano cheese and 1 1/2 tablespoons Parmigiano-Reggiano cheese. Arrange half of the in-shell clams (about 12 clams), with the clams facing up, over mixture in skillet; sprinkle evenly with 1/2 cup rice. Repeat layering process once with remaining half of onion mixture, remaining half of potatoes, remaining 1/2 teaspoon salt, remaining half of tomatoes, 1 1/2 tablespoons pecorino Romano cheese, 1 1/2 tablespoons Parmigiano-Reggiano cheese, remaining half of clams, and remaining 1/2 cup rice. Combine reserved clam cooking liquid (about 3/4 cup) and fish broth (about 3 cups) in a large measuring cup to equal 3 3/4 cups; pour broth mixture evenly over mixture in skillet. Cut a piece of parchment paper into an 11-inch circle, and place directly on mixture in skillet. Cover skillet with lid.
4. Place skillet in preheated oven, and bake until mixture is bubbling around edges and rice is almost cooked through, about 1 hour. Remove lid, and discard parchment paper. Return skillet to oven, and bake, uncovered, at 325°F until liquid has fully absorbed, rice is tender, center is bubbling, and edges are caramelized, about 10 minutes. Remove skillet from oven, and sprinkle mixture evenly with remaining 1 tablespoon pecorino Romano and remaining 1 tablespoon Parmigiano-Reggiano. Return to oven, and increase oven temperature to broil. Broil, uncovered, until cheese has melted and top is golden brown, 6 to 8 minutes. Drizzle with remaining 1 tablespoon oil. Garnish with parsley, and serve immediately.