Peel and cube potatoes. Cover in water, add a dash of salt. Cook until tender. Drain potatoes well. Add butter, sour cream, onion, garlic, and 1/2 the cheese, salt (if needed) and pepper. Cream them like you would mashed potatoes. Cut bell peppers in half and scoop out the insides. Fill the peppers with the potato mixture and sprinkle remaining cheese on top. Broil until cheese melts and serve.