Cook the penne according to package directions, then drain and set aside.
In a large pan, drizzle in some olive oil. Once heated, add the sage leaves and cook until crispy, turning over at least once. This should take about 3-5 minutes. Remove the sage to a paper towel.
In the same pan, add the remaining olive oil. Sauté the garlic until fragrant, just 30 seconds.
Add diced butternut squash and cook for 5 minutes until lightly golden. Pour in vegetable stock to cover, bring to a boil, then simmer until the squash is soft, about 10 minutes.
Transfer the squash and some of the liquid to a blender and blend until smooth, adding more liquid if needed for a creamy consistency. Discard any extra liquid. Return the sauce to the pan and stir in grated Grana Padano. Add the pasta and toss to coat. Serve warm with extra cheese and crispy sage crumbled on top.