Preheat your oven to 430°F (220°C). Toss the diced sweet potatoes and minced garlic with olive oil, salt, and freshly ground black pepper in a large bowl. Spread the mixture on a baking sheet lined with parchment paper, ensuring the sweet potatoes are in a single layer. Roast for about 20-25 minutes until caramelized and tender, stirring halfway through.

While the sweet potatoes roast, bring a large pot of salted water to a boil. Add the short pasta and cook according to package instructions until al dente, usually around 8-10 minutes. Before draining, reserve about 2/3 cup of the pasta cooking water. Drain the pasta and set it aside.

In a large skillet, heat a combination of olive oil and unsalted butter over medium heat. Once the butter has melted, add the fresh sage leaves and fry for about 1-2 minutes until crispy and fragrant. Use a slotted spoon to transfer them to a paper towel-lined plate to drain excess oil.

In the same skillet with the remaining oil and butter, add the roasted sweet potatoes. Mash half gently with a fork or potato masher, creating a textured mix that will blend with the pasta.

Add the drained pasta to the skillet with the sweet potato mixture. Pour in the heavy cream and crumbled goat cheese, stirring continuously over low heat until the cheese melts and the sauce becomes creamy. Add reserved pasta cooking water gradually to achieve desired consistency.

Season your pasta with salt and freshly ground black pepper to taste. Serve warm, topped with crispy sage leaves, a drizzle of olive oil, and a sprinkle of grated Parmesan cheese if desired. Optionally, add a pinch of crushed red pepper flakes.