In medium bowl, combine flour, baking soda and salt; set aside.
In small bowl, mash bananas and lemon juice together; set aside.
In large bowl, use mixer to cream butter and honey. Add eggs and mix well. Stir in vanilla then milk. Gradually add flour mixture. Once combined, stir in mashed bananas.
Pour into slow cooker. Cover; cook on low 6 hours or high 4 hours, or until center of cake no longer looks gooey.
Uncover and let cake cool. Once completely cooled, frost cake and, if desired, top with sliced bananas and walnuts.
Notes
Notes: If adding bananas, do so just before serving or they will brown. If using a non-oval slow cooker, cook 1 hour less on high heat or 2 hours less on low heat.