Baked Radicchio and Mozzarella Pasta
2 tablespoons unsalted butter
2 medium garlic cloves, minced
1 medium white onion, small dice (about 1 cup)
7 medium Roma tomatoes (about 2 pounds), cored and coarsely chopped
3 heads Treviso radicchio (about 4 cups), ends trimmed and sliced crosswise into 1/2-inch strips
1/2 cup heavy cream
1 pound penne rigate or ziti pasta
8 ounces fresh mozzarella, small dice (about 1 1/2 cups)
1/2 cup finely grated Parmigiano-Reggiano
Heat the oven to 400°F and arrange a rack in the upper third. Bring a large pot of salted water to a boil over high heat.
Melt butter in a medium saucepan over medium heat. When it foams, add garlic and onion, season well with salt, and cook until translucent. Add tomatoes and let simmer until slightly reduced and thickened, about 10 minutes. Add radicchio and cream, and cook until radicchio is wilted, about 5 minutes. Taste and adjust seasoning as necessary.
Meanwhile, cook pasta in the salted water for about half the time recommended on the packaging and drain. (Do not rinse.) Set aside.
Once sauce has finished simmering, combine it with half-cooked pasta and mix until pasta is evenly coated. Place pasta mixture in a 13-by-9-inch baking dish and sprinkle mozzarella and Parmigiano over top. Place in the oven and bake until mixture is bubbling, pasta is al dente, and top is golden brown, about 20 minutes.