Almost exactly this. As the site says, they do taste much more buttery than actual hob nobs; I considered using coconut oil instead, which probably would have fixed that. Not that there's anything wrong with buttery, of course. Stay tuned for when these become part of ice cream sandwiches!
120 g oats
50 g white flour
50 g whole wheat flour
1/2 t baking powder
1/2 t baking soda
1/2 T wheat bran
75 g brown sugar
1 stick salted butter, cut into pieces
1/2 t vanilla
1/2 T corn syrup
3 oz dark chocolate, melted (6 squares of a TJ's pound plus bar)
Preheat the oven to 350F and get out the big food processor. (I ground the oats in the small food processor then mixed in the rest by hand, and that was the wrong choice.) Grind the oats until fine, then add the flours, leavening agents, and sugar, and process well. Add the butter, vanilla, and corn syrup, and process until coarse and crumbly.
Tear off two baking-sheet-size pieces of wax paper, get out the rolling pin, and line two baking sheets with parchment paper. Gather up a handful or few of dough, press into a mound in the middle of one piece of wax paper, top with the other piece, and use the rolling pin to mash the dough into a 1/4"-thick round. Cut out circles with a 1.5"-diameter glass (I used a liqueur glass), carefully transfer to the parchment-lined baking sheet, and press back into the cookie any bits that got dislodged in transit. Much of the dough left on the wax paper won't seem like it's buttery enough to ever stick together, but don't despair! Press even the driest-seeming bits together hard inside the wax paper, and a cookie will result. I got 33 cookies that didn't rise at all, so don't worry about leaving much space between them on the baking sheets.
Bake for 12 minutes until lightly golden around the edges. Transfer to cooling racks, and use a pastry brush to brush a thin layer of the melted chocolate onto each cookie. Let cool, then put in a tupperware to store.