Database

[{"name":"john","firstname":"doe","yearold":22,"recipes":[{"title":"cheesecake","data":[{"name":"egg","label":"Eggs for","value":6,"unit":"piece"},{"name":"oil","label":"Specific oil","unit":"oz","value":0.2},{"name":"flour","label":"Wholemel flour","value":450,"unit":"gr"}]},{"title":"cake","data":[{"name":"egg","label":"Eggs for","value":6,"unit":"piece"},{"name":"flour","label":"Wholemel flour","value":500,"unit":"gr"},]}]}]

Query

db.collection.aggregate([{$addFields:{recipes:{$map:{input:"$recipes",as:"recipe",in:{$mergeObjects:["$$recipe",{data:{$map:{input:"$$recipe.data",as:"datum",in:{"$mergeObjects":["$$datum",{$cond:[{"$setIsSubset":[["$$datum.name"],["egg"]]},{value:"#####"},{value:"$$datum.value"}]}]}}}}]}}}}}])

Result