Get data of object array Laravel

I have this object which I'm saving in the Session. This is my object Cart. As you can see there are three different arrays and I'm trying to get the attribute 'id' of the array 'item'.

How can I do that?

This is my code:

public function incrementQty(Request $request) {
        $id = request('product_id');
        $qty = request('qty');
        $cart = Session::get('cart');
}

via Chebli Mohamed