Preheat the oven to 425°F. Trim the top and bottom off the squash, and cut in half. Scoop and discard the pulp and seeds. Lay on a baking sheet, cut side up. Add butter to the center, sprinkle with salt and pepper, then bake until fork tender. Scoop out the flesh (with the melted butter) into a blender, and blend on high until smooth. Use some water or stock if necessary.

In one saucepan, bring the stock to a simmer. Keep hot.

In a separate saucepan, add enough canola oil to cover the bottom and warm over high heat. Once the oil is hot, add the farro and toast until golden. Transfer to a bowl and set aside. Lower heat to medium-high. Add 2 tablespoons of butter, then add the onions and cook until translucent. Add the garlic and cook until soft. Add a pinch of salt and stir. Add the farro back to the pan and drop the heat to medium. Ladle in about 1/2 cup of the hot stock into the farro, then stir until the liquid is absorbed. Continue to add one ladle of hot stock in at time, stirring until the liquid is completely absorbed. The farro will slowly expand and become creamy in texture like risotto. Once the stock is depleted, turn off the heat, and add the squash puree. Mix thoroughly, then add the kale and mix again. Add the butter and Parmesan, then season with salt to taste. 

You can use any type of mushrooms for this part: cut them into large pieces. Add a knob of butter to a hot saucepan, then toss in the mushrooms. The moisture from crowded mushrooms will prevent a good browning, so work in batches if you need to. Once the mushrooms have released some liquid, add a pinch of salt. Toss toss, taste. 

Top farrotto with cooked mushrooms, more grated Parmesan, and chives or green onions.