Cut off bigger and thicker swiss chard stalks. Place a large skillet with olive oil over medium-high heat. Add the swiss chard and spinach. Saute for a minute.
cook and serve
Add 60 ml or 1/4 cup water to the skillet along with the frozen peas. Continue to cook for 2 - 3 minutes. Then add the butter and lemon juice. Season with salt and pepper, stir to combine, and remove from the heat. Serve with your favorite main dish.