Prepare the roasted vegetables. Preheat the oven to 450° and line a baking sheet with parchment paper. Add the cut squash and onions to the baking sheet. Add all the other roasted vegetable ingredients and toss to combine. Bake for 30-40 minutes, tossing halfway through. Cook until lightly charred.
Meanwhile, make the risotto. In a small sauce pan over medium heat, add the oil and prepared onions. Cook for 3 minutes or until translucent. Add the garlic and a pinch of salt, and cook for 30 seconds more. Pour in the rice and wine, stirring to coat. Turn heat down to low to produce a simmer. Add the stock 1/2 cup at a time until nearly absorbed, checking every 5-8 minutes or so. Stir only if needed. This will take 20-30 minutes. Once all the stock has been added, taste to check the texture. Add additional stock as needed. The rice should be cooked through and creamy. At the very end, stir in the parmesan and heavy cream. Cook until just incorporated. Remove from heat.
About 10 minutes before serving, prepare the garnishes. On a preheated cast iron skillet over medium heat, add the bacon, cutting in half if need to fit. Cook until crispy on both sides. Remove from the pan to a paper towel. Chop roughly into strips. Evenly divide the risotto between two bowls. Top with the roasted vegetables, bacon, arugula, and additional parmesan. Add a couple fresh thyme leaves and cracked pepper if desired. Serve.