In a saucepan, sauté the onion in butter over low heat for 5 minutes. Add garlic and cook for 1 more minute. Add remaining ingredients and mix, being sure to break up the meat into small chunks. Cover the pot and cook over low heat for 30 minutes. Remove lid and continue cooking for 30 minutes. Stir several times while it cooks.
Pour mixture into a 23 cm x 13 cm (9 x 5-in.) loaf pan, or other small containers of choice, and press down firmly. Cover and refrigerate until completely chilled, about 4 hours.