The Sims 4's Baking Skill comes with the Get to Work Expansion Pack. This Skill adds a huge number of new recipes to the game, which can be sold via the Expansion's retail features. This allows players to make bakeries and other food-selling stores, and with huge profit margins so long as you are always baking new goods. This guide to Baking will provide some general tips on running a bakery, with the recipes that are unlocked as you level it.
How to: Baking Cheats
Press Control + Shift + C then type testingcheats on and press enter. You can now set your skill level with stats.set_skill_level major_baking x (fill in 1-10) - we also have a full listing of Skill Cheats and a master list of Cheats in The Sims 4
At time of writing, the ideal mood for Baking is broken - it displays as blue but doesn't give additional skill XP. It is likely meant to be Inspired, ala the base game's cooking skills. However, effective level from the Muser bonus trait -- gained by selecting a Creativity Aspiration upon Sim creation -- do kick in when Inspired. This gives you a 4-level advantage when cooking a meal, meaning it is more likely to come out high quality. Thus, methods of getting Inspired, as well as the Creative Trait are recommended.