[{"firstName":"John","lastName":"Doe","favoriteFoods":[{"name":"Cheeseburgers"},{"name":"Broccoli"},{"name":"Cheeseburgers"}]}]

db.collection.aggregate([{"$project":{"food":{"$filter":{"input":"$favoriteFoods","cond":{"$regexMatch":{"input":"$$this.name","regex":"chee","options":"i"}}}}}}])