There are two separate answers. If you have romantic interests then invite her to a special dinner. If on the other hand she is a friend who knows, thank her for the wonderful gift and have her over for a casual lunch. In both cases wear something that she has given you.
My experience women who receive gifts from other women don’t usually get garters unless it is a joke or for a bride, but you didn’t provide enough information to guess.
Face it she knows you wear women’s clothes. Wear one of the new skirts and dress appropriate. Act like it is normal wear. I have had several girls/women who knew and saw me dressed. I’ve always acted as though it was normal and they have recipicated.