Community Cook Book
I think a Community Cook Book (CCB) could be very useful and profitable. Make it an Opt-In feature that can be selected every time you make or modify a recipe. Make it searchable by Total Calories, Macro, and a Taste Rating. From there, a database of recipes displays. These CCB recipes are entered by Cronometer users as normal, but there is an added radio button to "Add Recipe to Community Cook Book?"
This could also turn into a physical, annual cookbook release by Cronometer. Best CCB Recipes of 2021, released around Christmas time or something. If the C-levels are really cool at Cronometer, they'll even find a way to reward those whose recipes get higher upvotes and are more valuable in selling the physical book and pulling in new Cronometer users.