Prepare your kale and feta stuffing first by heating oil and minced garlic in a sauté pan.Once you can smell the garlic and before it burns add your kale.Sauté the kale for about 5-8 minutes until almost wilted then add garlic powder, salt and feta cheese. Stir to combine.Continue to cook until feta is warmed through and kale is tender and wilted.Turn off heat and set aside.Preheat your grill to medium high heat.In a small bowl mix olive oil and garlic.Brush grates on grill with a little of the oil.Place your mushrooms on the grill and brush them lightly on top with the oil.Cook for about 5-8 minutes on this side then flip them over and brush them with the oil on the other side.Cook for another 5-8 minutes or until tender.Evenly divide your stuffing mixture on top of each mushroom.