Reduce heat to medium and add another tablespoon of olive oil. Add the kale, apple, cinnamon, lemon zest, and fresh rosemary to skillet and cook, stirring occasionally, until the apple is soft and the kale is just wilted, approximately 3-4 minutes. Season with salt and black pepper, to taste, and stir to combine. Remove from heat and transfer apple mixture to a medium-sized bowl and set aside.