Funky Chocolate Club

I don't know anything about that site, but I did take the GAS tour and I would personally hesitate to plan anything concrete out of the Lauterbrunen area on your own, as you won't know in advance what the weather will be like. I think you would be disappointed to leave the valley on a gorgeous day and travel to Interlaken for something like that, missing out on the stunning alpine scenery. On a rainy, cloudy day, maybe something like that would be great, but you won't know in advance. On our trip we had pretty bad weather in Switzerland, so on one day we went to the waterfalls and on the other day our guide planned a trip for us into Interlaken where we shopped and then he planned a chocolate shop tour and demonstration. It was a nice diversion for dreary weather but I never would have gone there if I could see the mountains.
So in short, yes, it is possible to do this, though someone else more experienced would have to tell you how to get there. But if it were me I wouldn't want to make any reservations and risk missing a beautiful day in Murren.

When I took that tour, there was plenty to occupy our free time when we stayed in Switzerland. The weather was perfect, so I enjoyed hiking and cow watching (more fun than it sounds) on our free day. There were plenty of little restaurants and snack places that had more than enough chocolate to satisfy our needs right there.

Funky Chocolate does sound like fun. You not only eat chocolate, you make it and decorate it according to their web site where you can find other details. Lots of hands on fun. But it is costly. And you will have to find transportation (an additional cost). It can be done, best bet would be on day 5 of the RS tour which is the free day to do what you want while in Switzerland.

What a shame to leave the gorgeous Swiss alpine mountains in order to attend an indoor chocolate craft program in the (not scenic) city of Interlaken. Here's my alternative suggestion so you'll get to see the special Swiss scenery while eating fabulous chocolate, too:
Take the cog rail train from Lauterbrunnen to the car-less village of Wengen, which is on the cliff just across the valley from Mürren. Walking on the main street from the cog rail train station to the cable car station, about half way there and on your left, is a wonderful patisserie and chocolate shop where they make their own fresh and delicious chocolate candies and truffles. Buy some (about 2 Swiss francs each = about $2.10) to eat on your way to see the alpine mountain views. Either walk uphill through the higher, quaint and pretty part of town, up a short trail to the Felix Mendolssohn monument with a stunning mountain view. Or, walk from the pastry/chocolate shop a little further uphill on the main street and take the cable car up to Männlichen for a different stunning mountain view, and amazing easy hiking trail. Or, if you don't want to hike, return to the cog rail train from the cable car station and from the chocolate shop, with plenty of chocolates in hand, and take the train further up the mountain to Kleine Scheidegg for a different spectacular view of the alps and pastures! That's on your way to the Jungfrau Mountain, if that's your destination, too.

What a shame to leave the gorgeous Swiss alpine mountains in order to
attend an indoor chocolate craft program in the (not scenic) city of
Interlaken.

Not scenic????? This looks pretty scenic to me:
https://goo.gl/maps/FQMN2GvHG6K2
While Interlaken may be a bit more commercial and busier than the mountain villages, it does have some pretty good views of the mountains and the two lakes it sits beside.
While I haven't been to the Funky Chocolate Club, I have visited other interactive chocolates attractions through out Europe, and have found them to very fun, educational, and of course very tasty. If it interests you go for it.
Interlaken isn't on Mars, it's a very easy 20 minutes train journey from Lauterbrunnen. One added bonus is that restaurant food in Interlaken is cheaper and more varied than what you will find on top of the mountains, so if you pair up the chocolate tour with lunch or an early dinner the excursion will be worth your time.

I have decided that I won't pass up mountain scenery for chocolate (as much as we all love chocolate). I'm hoping and praying for good weather on the trip, although if the weather is bad, I know the guide will make the best of it. I'm sure he or she will be providing goodies (including Swiss chocolate) during the trip.

Wise choice, Al. Enjoy the stunning scenery!
And you'll have plenty of opportunities to eat chocolate while in Switzerland, anyway--from breakfast with hot chocolate, to chocolate candy bars in shops all over (I recommend the Cailler brand, which is the premium line from Nestles, based in Switzerland) and homemade chocolates in patisseries (bakeries) and chocolate shops, to an ice cream sundae with chocolate sauce (order the Coupe Dänemark). You'll see chocolate everywhere -- it's Switzerland.

Tour is over, and we were blessed with cloudless skies on our first full day in Switzerland. Later in the day, just some fair-weather clouds to add some variety to the scenery. The second day was a bit cloudier, but that was fine, we explored the falls in the mountains that day. Just some rain sprinkles in the evening, when we went to Gimmelwald just to walk around and see it.

Maps can be deceiving. I didn't realize how far Lauterbrunnen is from Interlaken. It definitely would not have been worth it to go to the chocolate club unless the days were total washouts.

Thanks for reporting back, Al!
It sounds like you all had the best Swiss experience!

And, if you still want a chocolate fix you can make a quick trip from your home to Hershey PA.

Interlaken is a very very short 20 minutes away from Lauterbrunnen by train. However, any "pretty views" from Interlaken don't even come close to the stunning views from the alpine villages or Murren, Wengen, Lauterbrunnen. Like I've always said - Interlaken isn't bad...it's just that those alpine villages are just SOOOO much better.