Mix together garlic, onion, salt, pepper, brown sugar and Rotel in small bowl.
Place chicken in crockpot and add Rotel mixture on top.
Cook on low 6-7 hours or on high 3-4 hours.
Shred chicken well.
Preheat oven to 350 degrees.
Arrange chips in the bottom of a large baking sheet.
Spoon chicken mixture over tortilla chips.
Top with cheese and tomato (tomato optional)
Bake for 10 minutes or until cheese has melted.
Top with extra toppings, and enjoy!