[{"_id":1,"supermarkets":[{"groceries":[{"groceryType":"banana","groceryStockDate":"12345678","groceryAmount":12},{"groceryType":"cabbage","groceryStockDate":"313512","groceryAmount":53},{"groceryType":"strawberry","groceryStockDate":"51362","groceryAmount":52}]},{"groceries":[{"groceryType":"banana","groceryStockDate":"31321","groceryAmount":52},{"groceryType":"banana","groceryStockDate":"532451","groceryAmount":73},{"groceryType":"cucumber","groceryStockDate":"123","groceryAmount":12}]}]}]

db.collection.aggregate({$unwind:"$supermarkets"},{$unwind:"$supermarkets.groceries"},{$match:{"supermarkets.groceries.groceryType":"banana"}},{$project:{_id:0,groceries:"$supermarkets.groceries"}})