Sounds silly but once you have baked at least 1 of every cookie you can masterwork your oven and it only takes 10 Essence instead of 15. If you have multiple characters make sure to masterwork each oven, it is not automatic. Edit for clarification: once you have discovered a recipe it counts as 1 completed towards the masterwork. So If you already have some completed from last year, you only need to bake the new ones to masterwork your oven.