1. Preheat the oven to 375°F. Line a baking sheet with parchment paper. Brush the mushroom caps with the olive oil and season with salt and pepper. Transfer to the baking sheet. 2. In a medium saucepan, heat the broth over medium-low heat. Keep warm over low heat. 3. In another medium pot, melt the butter over medium heat. Add the onion and sauté until translucent, about 5 minutes. Add the garlic and sauté until fragrant, about 1 minute more. 4. Add the barley and cook for 45 seconds, stirring constantly. Add the white wine and bring to a simmer; stir until the wine is mostly absorbed by the grains. 5. Begin adding the broth in batches, 1 to 2 ladles full at a time. Stir the barley and broth frequently, allowing it to simmer vigorously. When the barley has absorbed almost all the broth, add another 1 to 2 ladles full and continue to stir until all the broth is absorbed. Continue until all of the broth is used and the barley is tender (if needed, use water to complete cooking). The process will take about 30 to 40 minutes. 6. Meanwhile, roast the mushrooms until they're just tender, 12 to 15 minutes. When you remove them from the oven, flip them over to allow any excess liquid or oil to drain out. 7. Stir the baby kale or spinach into the risotto until it's wilted. Add the thyme and rosemary; season with salt and pepper. Add the Parmesan and stir vigorously to combine. The risotto should look thick and creamy. 8. To serve, divide the risotto among the mushroom caps. Garnish the risotto with more Parmesan and parsley. Serve immediately.