1.cs

public class TicksToDateTimeCaller {

    private static DateTime TicksToDateTime(long ticks) {
        return new DateTime(ticks);
    }
    
    public TResult Call<T, TResult>(T arg) {
        return (TResult)(object)TicksToDateTime((long)(object)arg);
    }
}

2.cs

public class TicksToDateTimeCaller {
    
    private static class Cache<T, TResult> {
        public static Func<T, TResult> Call;
    }
    
    private static DateTime TicksToDateTime(long ticks) {
        return new DateTime(ticks);
    }
    
    static TicksToDateTimeCaller() {
        Cache<long, DateTime>.Call = TicksToDateTime;
    }
    
    public TResult Call<T, TResult>(T arg) {
        return Cache<T, TResult>.Call(arg);
    }
}