In a large pan, brown ground beef. Remove from pan and drain on paper towels. Add the butter to the pan drippings. Sauté the vegetables except for the potatoes. Cook until tender. Add the garlic and parsley with the meat into the pan. Pour in the broth and add the potatoes. Cook until potatoes are tender. Mix the flour and water together and pour over mixture. Bring to a boil until thickened. Reduce heat and add the Velveeta cubes along with the salt and pepper. Stir to melt cheese and add in the sour cream. Serve