Preheat your oven to 430°F (220°C). In a large bowl, toss diced sweet potatoes and minced garlic with olive oil, salt, and pepper, then spread on a baking sheet and roast for 20-25 minutes.

Bring salted water to a boil in a large pot. Add short pasta and cook according to package instructions until al dente, about 8-10 minutes. Reserve 2/3 cup of pasta water, then drain the pasta.

Heat a skillet with olive oil and butter over medium heat. Add sage leaves and fry for 1-2 minutes until crispy, then drain on paper towels.

Add roasted sweet potatoes to the skillet. Mash half of them with a fork, keeping the rest intact for texture.

Combine drained pasta with the mashed sweet potatoes in the skillet. Add heavy cream and crumble in goat cheese, mixing well. Use reserved pasta water to adjust sauce consistency.

Season with salt and pepper. Serve immediately, garnishing with crispy sage leaves and optional Parmesan cheese.