Bring a large pot of salted water to a vigorous boil. Add the rigatoni pasta and cook according to package instructions, about 10-12 minutes. Reserve ½ cup of pasta water, then drain.

In a skillet, melt 2 tablespoons of salted butter over medium heat. Add torn bread and toast until golden brown and crispy, about 4-5 minutes. Stir in 2 minced garlic cloves and a pinch of salt, sautéing for an additional minute.

In a separate pot, heat 2 tablespoons of olive oil over medium heat. Add 1 chopped shallot and cook until translucent, about 3-4 minutes. Stir in 2 minced garlic cloves, 1 tablespoon rosemary, and a pinch of red pepper flakes, and sauté for 1 minute.

Pour in 1 cup of pumpkin puree and 1 cup of vegetable broth. Whisk together until smooth, and bring to a gentle simmer. After 2-3 minutes, stir in ½ cup of heavy cream, seasoning with salt, black pepper, and nutmeg.

Add the cooked rigatoni pasta to the pumpkin sauce and toss to coat. If the sauce is too thick, stir in some reserved pasta water to reach desired consistency.

Remove from heat and sprinkle ½ cup of grated Parmesan over the pasta, gently folding it in to melt slightly. Serve warm, topped with garlic breadcrumbs and more Parmesan.