How to return "text/html" content for AJAX call using a template engine in sinatra?

SO, I have a problem with Ajax (using JQuery) and Sinatra.

I have a route:

get '/ajx' do
   content_type 'text/html', :charset => 'utf-8'
   slim :mypartitial, :layout => false
 end
 

which is to be called via Ajax "GET":

  $(document).ready(function() {
     $('#vars').click(function(event){
       $.ajax({  
         type: "GET",  
         url: "/ajx",  
         data: "",
         success: function(data) {  
           $("#result").html(data)
         }  
       }); 
     });
   });
 

But I get no html output and nothing is rendered. I suppose the problem is here

 slim :mypartitial, :layout => false
 

but I have no idea how to return a valid html still using the template engine.

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