high-protein butternut squash mac and cheese

0 Heat the oven to 425°F. Place the cottage cheese on the counter so it can start to come to room temperature. (This will help prevent it from separating when heated). 
1 Peel and seed the squash and cut into 1-inch cubes, if needed. Transfer to a large Dutch oven along with the garlic cloves. Drizzle with the oil and season with 1 teaspoon of the salt and several grinds pepper. Toss to coat. Roast, covered, until the squash is very tender (a knife easily slides through), 35 to 45 minutes. Uncover and set aside to cool for 5 minutes. 
2 Meanwhile, bring a large pot of salted water to a boil. Cook the pasta according to package directions for al dente. Drain and spread onto a sheet pan to cool (this will prevent the noodles from sticking together). 
3 If using an immersion blender: Add the cottage cheese, milk, nutmeg, cayenne, 1/2 teaspoon salt, and several grinds pepper to the Dutch oven with the roasted squash. Blend until smooth, adding more milk as needed. If using a stand blender: Transfer the roasted squash and garlic to a blender. Add the cottage cheese, milk, nutmeg, cayenne, 1/2 teaspoon salt, and several grinds pepper. Blend until smooth, adding more milk as needed. Return to the Dutch oven. 
4 Place the Dutch oven over medium-low heat to warm up the sauce (it should be steaming and very gently bubbling, but it should not be rapidly bubbling). Remove from the heat and add the cheddar and Parmesan cheeses a handful at a time, stirring after each addition, about 5 minutes total. If the cheese isn't melting fully, you can return the pot to low heat. (You just don't want to overheat the sauce, as that's when you risk the cottage cheese separating). Taste and season with more salt, pepper, nutmeg, and/or cayenne. 
5 Add the cooked pasta and toss to coat. If the sauce seems thick, add more milk a little bit at a time until it reaches your desired consistency. Serve warm, with more freshly-ground black pepper.