Deeply flavored and meaty and glorious, hen of the woods (a.k.a. maitake) can be found at most mainstream grocery stores or at the farmers’ market. Don’t chop them! Pull them into strips.
Preheat oven to 450°.
Bring a large pot of water to a boil for the farro. Salt the water and add the farro, onion, and bay leaves. Cook until the farro is al dente, about 20 minutes. Drain and discard the onion and bay leaves.
Meanwhile, on a rimmed baking sheet, arrange the hen of the woods mushrooms and the sliced shallot. Spray with cooking spray or toss with oil; season liberally with salt and pepper. Roast until crisp, turning once, 17 to 18 minutes. Place the nuts on another rimmed baking sheet. Roast until toasted, about 5 minutes.
In a small saucepan, bring the stock and porcini mushrooms to a boil. Reduce heat to medium-low. Simmer until the porcini are soft, about 5 minutes.
In a large skillet, heat the oil, three turns of the pan, over medium-high. Add the cremini mushrooms. Cook, stirring occasionally, until browned, about 8 minutes. Add the chopped shallot, garlic, and thyme; season. Cook, stirring often, until fragrant, a minute or two. Add the wine. Increase heat a bit and stir until the wine evaporates, about 1 minute.
Add the farro to the skillet. Using a slotted spoon, transfer the porcini from the stock to a cutting board. Chop the porcini. Add to the skillet with the cremini and farro. Pour enough of the porcini soaking liquid into a measuring cup to measure 1 cup and add to the farro. Mix in the nuts, Parm, and kale. Cook, stirring often, until the Parm melts and the kale wilts, about 2 minutes. Mix in the lemon juice. Spoon into shallow bowls or transfer to a serving platter. Top with the crispy mushrooms and shallots.