Help with Core2.0, Azure Authentication and REST call

I started with the basic ASP.NET Core 2.0 with Azure Authentication. Everything works in a web browser. It starts up, browser goes to MS, signs in and returns to the app. So far so good.

What I want to do is then use PowerShell with Invoke-RestMethod to connect to the same application. I appear to be missing something. Best guess is i need to enable something in the startup.cs file related to tokens or another authentication method?? Alternatively I've just made a hash of my authentication header.

$loginURL = "https://login.microsoftonline.com/"$clientId = "Client ID"$clientSecret = "Secret ID"$resource="https://tenantname.onmicrosoft.com/WebApplication1"$body=@{grant_type="client_credentials";client_id=$clientId;client_secret=$clientSecret;resource=$resource}$tenant = "tenantname.onmicrosoft.com"$token = Invoke-RestMethod -Method Post -Uri $loginURL/$tenant/oauth2/token?api-version=1.0 -Body $Body

I get my token back, all seems fine at this point.

$authHeader = @{
     'Content-Type'  = 'application\json'
     'Authorization' = 'bearer ' + $($token.access_token)
     'Expires'       = $token.expires_on
}
Invoke-RestMethod -Method Get -Uri https://localhost:44342/api/id -Headers $authHeader -Verbose

And this is where it returns a 55K HTML text string from MS instead of a 200 OK.

I repeated the post to the application in Postman and it came back with a preview of, "we can't sign you in, browser blocks javascript." As I understand it, I shouldn't be at MS in the first place. The application should have taken the token and executed the request.

Do I need to add an authentication method to the startup.cs? I've tried different header values to no avail. Hopefully its just me being a newbie with Core 2.0 in general. I have been searching for different articles online to cover this dual purpose access, Browser and API when Azure provides the authentication service but I just haven't found anything that matches or appears to match. 

Help appreciated! Thank you.

Startup.cs

public class Startup
    {
        public Startup(IConfiguration configuration)
        {
            Configuration = configuration;
        }

        public IConfiguration Configuration { get; }

        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddAuthentication(sharedOptions =>
            {
                sharedOptions.DefaultScheme = CookieAuthenticationDefaults.AuthenticationScheme;
                sharedOptions.DefaultChallengeScheme = OpenIdConnectDefaults.AuthenticationScheme;
            })
            .AddAzureAd(options => Configuration.Bind("AzureAd", options))
            .AddCookie();

            services.AddMvc();
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IHostingEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
                app.UseBrowserLink();
            }
            else
            {
                app.UseExceptionHandler("/Home/Error");
            }

            app.UseStaticFiles();

            app.UseAuthentication();

            app.UseMvc(routes =>
            {
                routes.MapRoute(
                    name: "default",
                    template: "{controller=Home}/{action=Index}/{id?}");
            });
        }
    }