Mongodb nested object

I have this cart application working that creates and saves the final order as this, for example:

{
   "_id":"5cec38fd15cf18372423689e",
   "user":"5be317a2296edb1717581514",
   "email":"email@email.com",
   "dateOrder":"2019-05-27T19:22:37.051Z",
   "cart":{
      "items":{
         "5bd727ff4d2d4f6d27973b18":{
            "item":{
               "_id":"5bd727ff4d2d4f6d27973b18",
               "title":"Banderitas 45*12 x 200 POP-UP FLAGS STICK´N\t407",
               "description":"postit post it notas POP-UP FLAGS STICK N STICKN",
               "imagePath":"banderitas-4512-x-200.jpg",
               "location":"2/077",
               "stock":4,
               "minimumStock":5,
               "lastModified":"2019-02-13T14:06:14.000Z",
               "__v":0,
               "tempStock":0
            },
            "qty":1
         },
         "5bd727ff4d2d4f6d27973afe":{
            "item":{
               "_id":"5bd727ff4d2d4f6d27973afe",
               "title":"Lápiz corrector ",
               "description":"liquid paper corrector lapiz corrector sylvapen berol",
               "imagePath":"corrector-lapiz-sylvapen-7-ml.jpg",
               "location":"2/077",
               "stock":6,
               "minimumStock":10,
               "lastModified":"2019-05-27T14:15:29.000Z",
               "__v":0,
               "tempStock":0
            },
            "qty":1
         },
         "5bd727ff4d2d4f6d27973b39":{
            "item":{
               "_id":"5bd727ff4d2d4f6d27973b39",
               "title":"Bolígrafo UNI-185 0.5 mm Azul",
               "description":"boligrafo birome azul Bolígrafo UNI-185 0.5 mm Azul",
               "imagePath":"boligrafo-uni-185-05-mm-azul.jpg",
               "location":"2/077",
               "stock":21,
               "minimumStock":12,
               "lastModified":"2018-12-05T12:30:00.000Z",
               "__v":0,
               "tempStock":0
            },
            "qty":1
         },
         "5bd727ff4d2d4f6d27973ac0":{
            "item":{
               "_id":"5bd727ff4d2d4f6d27973ac0",
               "title":"Tinta Pelikan 957 4K 28cc Negro",
               "description":"tinta pelikan sellos negro negra",
               "imagePath":"tinta-pelikan-4k-28cc-rojo.jpg",
               "location":"2/076",
               "stock":2,
               "minimumStock":0,
               "lastModified":"2018-11-08T18:08:13.000Z",
               "__v":0,
               "tempStock":0
            },
            "qty":1
         }
      },
      "totalQty":4
   },
   "__v":0
}

Now, I can’t figure out how to iterate with JS or access with Mongodb all my orders to access the nested object item.title value to get the most purchased items statistic. I’m trying to manipulate the data using Cube.js or the Mongodb Compass client, but they truth is that I don’t know where to beging.