Chemin du Gruyère: The Swiss Chocolate and Cheese Trail
The Chemin du Gruyère takes you on a hike from Charmey to Gruyères and you can visit the Chocolate Factory in Broc and the Cheese Factory in Gruyères on your way.

You would start the hike in Charmey at the Post Office, and will find more details about this venture at http://www.myswitzerland.com/en-us/chemin-du-gruyere-the-swiss-chocolate-and-cheese-trail.html

In order to get to Charmey from Montreux, you have the following connections, leaving Montreux at 8:18 AM (the same connections are available one hour later and so on, that is at 9:18 AM, 10:18 AM, etc.:

Return to Montreux
Then in the afternoon from Gruyeres to Montreux, you would take the train to Montbovon where you change for a train to Montreux. They leave Gruyeres at 2:59 PM, 3:59 PM, 4:59 PM etc.: