User defined stored procedure - where's the execution plan?

Question

SQL Server 2016, Enterprise Edition in Windows

Is there anyway to display the execution plan of a stored procedure created in C# with Visual Studio Data Tools? This is a question that someone with Visual Studio experience probably knows the answer to. My searches on Google haven't turned up anything useful.

Here is the stored procedure in c#

using System;
using System.Data;
using System.Data.SqlClient;
using System.Data.SqlTypes;
using Microsoft.SqlServer.Server;

public partial class StoredProcedures
{
    [Microsoft.SqlServer.Server.SqlProcedure]
    static public void Addition (SqlInt32 a1, SqlInt32 a2, out SqlInt32 sum)
    {
        sum = a1 + a2;
    }


}

Here is the execution in SSMS 2017 v17.3

USE CLR1;

declare @sum int
exec dbo.Addition 3, 4, @sum output
select @sum

I have also been able to find the execution plan in cache. Even though there is a plan_handle available in dm_exec_procedure_stats, I can't seem to use a cross apply to [dm_exec_query_plan] to view it.