How to Make It
Preheat the oven to 400°F.
Toss the squash on a baking sheet with 2 tablespoons of the oil and 1/2 teaspoon each salt and pepper. Remove the top of the garlic head and sprinkle the exposed cloves with a pinch of salt, then wrap the garlic in aluminum foil and place it on the sheet with the squash. Roast the squash and garlic until the squash is tender and golden brown and the garlic is golden, 35 to 40 minutes.
While the squash roasts, heat the stock over low heat. Heat the remaining 2 tablespoons oil in a medium heavy pot over medium high heat until hot, then add the onion and 1/2 teaspoon each salt and pepper, and cook, stirring occasionally until golden, about 6 minutes. Stir in the quinoa and bay leaf, then add about 1 cup of the stock and simmer, stirring occasionally, adding more stock as needed, 1/2 cup at a time, until the quinoa is tender, 30 to 35 minutes. Squeeze the garlic cloves from their skins and stir into the risotto, then add the baby arugula and cook, until wilted, about 2 minutes. Stir in the squash, butter, and cheese. Season with salt and pepper to taste, then serve.