Cook bacon as directed on package until crispy; set aside.
While bacon cooks, mash avocado in a small bowl. Chop basil and add to avocado along with mayo, minced garlic, salt and pepper; mix well.
Toast bread and slice tomato. Spread avocado mixture onto each slice of bread. Add bacon, tomato, lettuce, and alfalfa sprouts to 1/2 the toast; top off each with a second slice. Cut sandwiches in half and serve with grapes.