In a large deep skillet, cast-iron skillet, or Dutch oven, heat 3 tbsp. EVOO, three turns of the pan, over medium. Add onion, chard stems, and a pinch of salt and cook for a few minutes, until starting to soften. Add garlic and Aleppo pepper and stir for 1 minute. Pour in stock, then stir in the chard and kale leaves. Season with nutmeg. Cover and simmer until wilted and tender, 7 to 8 minutes. Stir in the spinach and herbs; cook until spinach is wilted, 2 to 3 minutes. Turn off heat and stir in lemon juice and remaining 2 tbsp. EVOO. Serve with rice or charred bread.