In a large, heavy pot, heat olive oil over medium heat. Add garlic and crushed red pepper and sauté for 1 minute, until garlic is fragrant. Add squash; stir to coat with oil, and add 2 tablespoons cooking liquid. Cover and cook for 4 minutes, stirring frequently and adding more cooking liquid if needed to prevent sticking. Add kale, sprinkle with sea salt, and stir to coat. Cover and cook for 3–4 minutes, until just tender. Add chard; stir and cook for 1–2 minutes, until wilted. Season with salt and pepper, and serve.