access cookie in _Layout.cshtml in ASP.NET Core

So I found the solution, if anyone needs it, too:

Add into ConfigureServices the service for IHttpContextAccessor

public void ConfigureServices(IServiceCollection services)
{
    services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();
}

into your _Layout.cs inject IHttpContextAccessor:

@inject IHttpContextAccessor httpContextaccessor

access the cookies with

@Html.Raw(httpContextaccessor.HttpContext.Request.Cookies["Bearer"])

In ASP.NET Core there is no concept of a static HttpContext any more. Dependency Injection rules in the new Microsoft Web Framework. Regarding views there is the @inject directive for accessing registered services like IHttpContextAccessor service (https://docs.asp.net/en/latest/mvc/views/dependency-injection.html).

Using the IHttpContextAccessor you can get the HttpContext and the cookie information like in this example.

 @inject Microsoft.AspNetCore.Http.IHttpContextAccessor HttpContextAccessor

 @{
    foreach (var cookie in HttpContextAccessor.HttpContext.Request.Cookies)
    {
        @cookie.Key  @cookie.Value
    }
}