Butternut Squash Parmesan

Preheat oven to 425°. Heat 1 Tbsp. oil in a medium saucepan over medium. Cook anchovies, garlic, and red pepper flakes, stirring often with a wooden spoon, until sizzling, 30–60 seconds. Add tomatoes and gently break apart with spoon. Reduce heat to low and bring sauce to a low simmer. Cook, stirring occasionally, until sauce is slightly thickened and flavors have melded, about 15 minutes.

Meanwhile, cut off neck from squash. Peel neck and bulb until you reveal the orange flesh underneath (you might need to take off a few layers). Stand bulb upright on cut end. Starting on one side, slice top to bottom into ¼"-thick planks until you reach the core (you don’t want holes or seeds in your squash). Rotate squash and repeat until you’ve worked all the way around the bulb. Slice neck in half lengthwise, then cut crosswise into ¼"-thick pieces. Transfer squash to a large bowl. Add 2 Tbsp. oil and 1½ tsp. salt and toss to coat.

Mix mozzarella, Parmesan, and yogurt in a small bowl; season with salt and black pepper.

Using an immersion blender directly in pot or transferring tomato sauce to a food processor, purée until mostly smooth. Taste and season with salt and black pepper.

Drizzle 1 Tbsp. oil in an 8x8" glass or metal baking dish. Spread with ½ cup sauce. Arrange 5–6 squash pieces in a mostly even layer over sauce (it’s okay if some pieces overlap). Sprinkle with ½ cup cheese mixture, then spread with ½ cup sauce. Layer again with squash, followed by ½ cup cheese mixture and ½ cup sauce. Repeat with a final layer of squash and remaining cheese mixture and sauce.

Cover pan with foil and bake 50 minutes. Uncover and continue to bake until cheese is browned and sauce is bubbling, 15–20 minutes.

Meanwhile, toss panko and remaining 2 Tbsp. oil and ½ tsp. salt in a small bowl with your hands until well coated.

Top squash Parmesan with breadcrumb mixture and continue to bake until golden brown, about 10 minutes (don't worry if things look liquidy; the breadcrumbs and squash will soak them up as everything rests). Tear basil leaves over. Let cool 10 minutes before serving.

Do Ahead: Sauce can be made 3 days ahead. Cover and chill. Unbaked squash Parmesan (without panko) can be assembled 8 hours ahead. Cover and chill.