How can I use two projections in MongoDB at the same time?

I have documents I need to retrieve data from in this format:

{
    "id": ObjectId("alskdjflqkjwr23"),
    "field1": {
        "morefields": values
    },
    "field2": {
        "morefields": values
    },
    "field3": {
        "morefields": values
    },
    "field14": {
        "morefields": values
    },
    "importantField": {
        "subfield1": values,
        "subfield2": values,
        "importantArray": [
            {
                "subsubfield1": values,
                "importantSubArray": [
                    {
                        "subsubsubfield1": values,
                        "subsubsubfield2": values
                    },
                    {
                        "subsubsubfield1": values,
                        "subsubsubfield2": values
                    }
                ],
                "importantValue": values
            },
            {
                "subsubfield1": values,
                "subsubfield2": values,
                "subsubfield3": values
            }
        ]
    }
}

I need the importantValue and elements in the importantSubArray fields, but I can't get my query to return what I need without all of the extra data in the other fields. I just started using Mongo a week ago.

I have tried this query, but only one of the projections works, depending on which order I put them in. So I can either return only the array within importantField, but all 400 or so elements, not just the last 2, or I can return the last 2 elements of importantField.importantArray, but also return all of the other fields, subfields, subsubfields etc.

db.getCollection("my_data").find({}, 
    { 
        "importantField.importantArray" : 1.0,
        "importantField.importantArray": { $slice: -2 }
    }
);

How can I get both of these to work at the same time? Thanks.

EDIT:

The expected output should look like this. I need the elements in importantSubArray array and importantValue field

{
    "importantSubArray": [
       {
            "stuff": morestuff
       },
    ],
    "importantValue": value

I was able to combine the comment from @prasad_ with a slice by using an aggregation and projecting the fields I want in the first stage and then doing another projection in stage 2 and slicing for the last 2 elements.