1. Using a fork mash the seeded avocados in a bowl. Add the onion, garlic, jalapeno, cilantro, lime juice, salt and pepper. Stir until well combined then add the chopped tomato and stir.
2. Heat a fry pan to medium-high heat. You may want to add a bit of butter to the pan at this point. Spread desired amount of guacamole (or if you want you can just use sliced avocado and sliced tomatoes) on the bread then top with cheese. Butter the outside of the bread and grill on one side for about 2-3 minutes or until golden and crispy. Flip the sandwich and grill until golden brown. Continue the same process for the other sandwich. Cut and serve warm.