Roast the Squash
Preheat the oven to 425° F and line a baking sheet with parchment paper.
Toss the cubed squash with olive oil, along with a pinch of salt and a couple grinds of black pepper.
Roast for 30-40 minutes, or until the squash is fork-tender, flipping once about halfway through. Let cool for at least 10 minutes.
Cook the Pasta
Cook the pasta according to the package directions; drain
Prepare the Cheese Sauce
In a saucepan, over medium-low heat, add a Tbsp of olive oil, the almond milk, and arrowroot powder. Whisk until the clumps are gone. (~ 1-2 minutes)
Add to the saucepan the remaining ingredients: nutritional yeast, mustard, garlic, lemon, a pinch of salt, and pepper. Whisk continuously, until thickened (~ 5-7 minutes)
To a food processor (or blender) add 1 ½ cups of the roasted squash, along with the thickened sauce, and process until smooth.
Combine and Bake
Combine the cooked pasta and the desired amount of cheese sauce in a bowl.
Line a baking sheet with parchment paper. Spread the macaroni mixture and scatter breadcrumbs evenly over the top.
Bake for 25 to 30 minutes, or until it's golden and the macaroni is bubbling.
Let sit 10 minutes before serving