best flapjack recipe: does it exist?

[sonsmum]

If I use rolled oats, the flapjack is dense, firm but a little tasteless.
If i use jumbo oats, the flapjack falls apart.
I had a recipe that used both types of oats, but alas I have lost the recipe!
I can't re-create it, and am wasting oats, golden syrup, sugar and baking marg on sub-standard results.
My flapjacks tend to turn into granola .
Please share your foolproof flapjack recipes, including what temperature you put the oven on at, cooking time, and size of baking tin, thanks!
I have sporty kids and flapjacks are a perfect pre-sport snack!

Just made some using @SoupDragon 's recipe - and it is so delicious that I can't see the double batch I made lasting long

I make this flapjack recipe from the Lyle's syrup website:

www.lylesgoldensyrup.com/recipe/flapjacks

But I subtract about 50g of the oats and add plain flour instead as I like my flapjacks a bit more solid- like you'd get from a local bakery.

I have used Soup Dragon's recipe 4 x now and have varied it by adding raisins and then sprinkling chocolate nibs on it after it came out if the oven and had cooled slightly.
Another time I added chopped stem ginger and some of the syrup from the jar instead of a bit of condensed milk - then did the same thing with chocolate nibs.
Another time, I replaced 30g of the oats with 30g of ground almonds and added chopped glace cherries- then same thing with the chocolate nibs. They have all worked out really well and been eaten with delight by DC, DH, PIL, DH's grandma, the gardener and my friends at painting.

The stem ginger chopped into the condensed milk 😋😋😋

I've made @SoupDragon 's recipe a number of times now. It is an absolute gamechanger - this is what I want flapjacks to taste like! Even DH will have them (and he's really fussy about that sort of thing, constantly buying ridiculously expensive power bars for when he goes biking). DS1 has them for school. I have them for my morning coffee at work.
I swap 1/3 of the oats for Alpen (no sugar) muesli and have reduced the amount of butter by 25g (but only so that when I make it (I always make double) I can simply use a 250g block of butter).
Absolute perfection. THANK YOU!

I’ve made @SoupDragon ’s one for years but I’ve also tried this worthy type one which is also v good if you like PB. I up the PB and honey a bit to make it extra chewy.