Heat oven to 375 degrees. In a large Dutch oven, heat oil over medium. Add onion and cook, stirring occasionally, until softened, about 3 minutes. Add garlic and stir until fragrant, 1 minute. Add rice, season with salt and pepper, and stir until coated in oil and lightly toasted, 2 minutes.
Add kale, season with salt and pepper, and stir until wilted, 30 seconds. Add broth and bring to a boil over high heat.
Cover and bake until almost all of the liquid is absorbed and rice is tender, about 20 minutes.
Stir in spinach and peas until spinach is wilted. Add Parmesan, butter and lemon juice, and stir until well blended and saucy. (Liquid will continue to absorb as risotto sits.) Season with salt and pepper. Serve in bowls and top with more Parmesan.