Create Stored Procedures using Entity Framework Code First?

Instead of using StringBuilder you can use existing EF methods

public override void Up() 
{
  CreateStoredProcedure(
    "MyStoredProcedure",
    p => new
    {
        id = p.Int()
    },
    @"SELECT some-data FROM my-table WHERE id = @id"
  );
}

public override void Down() 
{
  DropStoredProcedure("MyStoredProcedure");
}