Add potatoes and chicken broth in a large microwave-safe bowl and cover. Microwave on high for 15 minutes or until soft when pierced with a knife. Mash. Stir in milk, herbs, salt and pepper.
While the potatoes are cooking, heat olive oil in a large skillet over medium heat. Add onions and cook for 15 minutes, stirring frequently. Add in garlic and stir. Cook 5 more minutes.
Add kale to skillet and cook for 2 minutes until wilted, stirring frequently. Add kale mixture to potatoes and stir to combine. Transfer to a serving bowl and serve hot.