Cook first 5 ingredients in a large saucepan over medium-low heat, whisking constantly, 15 to 20 minutes or until thickened. Remove from heat; whisk in peanut butter until blended. Stir in diced bananas and vanilla.
Combine peanuts and vanilla wafers. Divide 1 cup peanut mixture among 10 (8-oz.) jars. Top with pudding mixture and remaining peanut mixture. Cover and chill 2 to 24 hours.