Updated 01-14-2016 09:32 PM
To evolve a Hoghurt you must feed a Rashberry cheesecake. To make cheesecake, first buy some milk from the produce section of Costolot's store which is available when you reach level 11. Have Bart tinker the milk which will turn it into cheese. Have Bart then tinker the cheese and it will turn into cheesecake. Feed the cheesecake to a Rashberry and it will evolve.