Heat the oven to 400°F. Drizzle the squash with olive oil and sprinkle with brown sugar. Season with salt and pepper . Set the acorn squash halves cut-side up in a baking dish. Roast in the oven for 35 to 45 minutes, until they are fork-tender and the edges look roasted and slightly caramelized. Set aside.
In a large non-stick skillet over medium heat, melt the butter. Add the garlic and onions, and saute for about 2 minutes, until the onions are translucent. Add the arborio rice, stir to coat with butter for 2 minutes.
Add the vegetable broth, 1/2 cup at a time, and stir until all the liquid is absorbed before adding another 1/2 cup. I found it best to add 1/2 cup of broth every 4 minutes until all the broth is done and the rice becomes creamy.
Then, add the Parmesan cheese, stir to incorporate, season with salt and pepper and remove from the heat. You may add another 1/4 to 1/2 cup of broth if you feel that the mixture is too dry at this point.
Once you reach the desired consistency, stuff the roasted squash halves with the Parmesan risotto. Then, garnish with the basil and crushed red pepper, if you desire. Serve as a side course with protein of choice.