TLDR: The Great British Baking Show baking sheets are Silverwood 15X13 inch heavy duty baking sheets (Not available on US or UK Amazon).
Every. Single. Episode. The bakers on The Great British Baking Show use their Silverwood 15X13 inch heavy duty baking sheets (Not available on Amazon).
These are not made of pure silver as their name would imply - I'm just as disappointed as you. Instead the Silverwood 15X13 inch heavy duty baking sheets are made out of anodized Aluminium. I first noticed these trays for two reasons, first being Aluminium they stand out quite brightly. Secondly I noticed they do not have a rim, instead only a single back-wall. This allows for easily sliding things off the pan, think cookies and bread right onto a cooling rack. If we have learned anything from The Great British Baking Show, it also allows for things to easily slide off on their own accord... onto the floor.
These pans are hand crafted using 'traditional methods' and are designed to last a 'lifetime.' Whenever I see this statement I immediately look at their warranty and what it entails - Silverwood backs their pans with a 25 year warranty. Not bad - I guess the pans have about the same 'lifetime' as a Jack Russel Terrier.
The pans have an alloy core which helps with even heat distribution. Regardless, being Aluminium they should transfer heat really well compared to other materials and will not rust. Silverwood also claims the pans will never warp or distort. Silverwood has another line of "Aga baking sheets" which have an endorsement by Mary Berry (I miss her on the show) which are supposed to be able to handle being in the oven and then dunked in water and not warp. Bold claims, and the engineer in me really wants to try this.
The Silverwood baking sheets are not dishwasher safe, though come to think of it I'm not sure they'd fit, and secondly who runs baking sheets through the dishwasher? Silverwood claims the pans are incredibly easy to clean. Because they're Aluminium and should have been coated with something to help what ever you're baking release, a quick soak, soap, and a sponge should do the trick when it comes to cleaning.
Being Aluminium, they do not take too kindly to highly acidic foods (think roasted tomatoes), and will discolor and eventually corrode after enough acidic use, so best to avoid those bakes on these pans if you can.
Also if you've never tried a baking parchment - its time to change your life for the better, forever. These make sure nothing sticks and make clean up take sometimes take literally 5 seconds. I've linked to the Reynolds Kitchens Cookie Baking Sheets, Pre-Cut Parchment Paper because they come in sheets instead of rolls. This means they lay flat instead of trying to roll up once you cut it, which is another one of those nice things that after you experience, you'll never go back.
Silverwood was formed in 1960 in Birmingham England and refuses to compromise.
While a lot of other bakeware manufacturers outsourced their production in search of cheaper materials, mass production, and labor costs, Silverwood decided to stay in England. They continue to to craft their bakeware with traditional methods, which includes manual operation of machinery and hand-finishing the products. This is kind of incredible in today's day and age.
Because of this, the quality and durability of their bakeware is second to none. With the heavy use that the baking sheets on The Great British Baking Show undergo, they need a high quality and durable baking sheet. A cheaper sheet would find itself in baking heaven quite readily.
But with quality comes cost. The Great British Baking Show probably does not sweat the cost of baking sheets, but you may. They clock in at £23.95 GBP, which is roughly $35 US. However, if you take the plunge (you should), you'll have these pans longer than your Jack Russel Terrier, and that is just under warranty! They may be something you hand down to your future bakers.
Nordicware Naturals® Insulated Baking Sheet - The best & easiest to get in the US (Amazon Link)
Sadly, here comes the bad news. Silverwood only sells their bakeware in the UK and at Lindy's Cakes Ltd in Australia (Showing love for the former prison colony - classy move). They do not sell on US or UK Amazon, which means you need to go directly through Silverwood or a reseller.
Here comes the good news! They ship internationally!
Bad news - it is £23.95 GBP for shipping. That's like $50. Ugh.
So what to do? Well do you have baking friends? Put together an order and get like 2 pans for each person in your party and split shipping.
Or if this just seems too much of a hassle there are some decent options out there.
If you head to Walmart... or Target, or Macy's, or possibly even your local grocer, you can get your very own really cheap baking sheets today. I'm sure of it. I've done it.
I've been baking on the same Oneida baking sheet for the last 10 or so years - maybe 15?. Its steel, and at this point is seasoned beyond recognition. I love it. It also makes a very satisfying "BLANG" sound after about 2 minutes in the oven when it warps into a Pringle. The sound is accompanied by a slight creaking when you take it out of the oven. It's alarming.
So if loud noises in your oven are part of your dream setup go for it! If not, lets take a look at a nice option.
Nordicware Naturals® Insulated Baking Sheet (Amazon Link) is very similar in form to the Silverwood baking sheet. However, this has an air pocket instead of an alloy at it's core. This slightly insulates the baking surface and prevents the bottoms of cookies and breads from burning. If you have hot spots in your oven this is awesome.
Secondly there is the Nordicware Naturals® Baker's Half Sheet (Amazon Link). These have been raved about by - well nearly everyone - with over 27,000 5 star reviews on Amazon alone they stand alone as an amazing option. Nearly ever "best baking" sheet review lists these at the top by a large margin. They have a full 1 inch rim, so things are not going to slide off (for better or worse) and a steel bead in the rim to make sure that it does not warp. They have roughly the same surface as the Silverwood trays so you should take care of them in similar ways (hand-wash, low acid, & love). They also are priced at roughly $30 for a set of two.
If you're wondering what a "half sheet" is and if this is the size you want, it probably is. It measures 13x18 inches and is more than likely the size of every baking sheet you've ever seen, unless you work in an professional kitchen.
All this said, if you're in the UK and can easily get your hands on Silverwood bakeware - do it! If you're outside the UK it may be a bit harder but well worth it - especially if you're looking to use the same baking sheets as bakers on The Great British Baking Show. If you just cant stomach the cost, the Nordicware option is great. And if you're like me, don't scare easily at loud bangs in your oven, you can always head to any department store and get something really cheap.
My well seasoned Oneida baking sheet. It's fine. (Amazon Link)