using System;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        var original = new List<Dictionary<string, double>>();

        Wut(original);

    }

    private static void Wut(object theThing)

    {

        List<Dictionary<string, double>> real = (List<Dictionary<string, double>>)theThing;

        real.Add(new Dictionary<string, double>(){

            {"theKey", 2.2}

                                                 });

        Console.WriteLine(real);

    }

}