Preheat your oven to 240°C/220°C fan/gas mark 9.
Chop the potatoes into 3cm chunks (no need to peel). Pop onto a large baking tray. Drizzle with oil, season with salt and pepper then toss to coat. Spread out in a single layer. TIP: Use two baking trays if necessary.
When the oven is hot, roast on the top shelf for 20 mins - you'll roast them for longer once you've crushed them.

While the potatoes roast, quarter the pear lengthways, remove the core and chop into small pieces (no need to peel).
Trim the baby gem, separate the leaves, then tear into bite sized pieces.

Put the wholegrain mustard, Dijon mustard and cider vinegar into a large bowl. Add the sugar and olive oil for the dressing (see ingredients for both amounts).
Season with salt and pepper, mix together and set your mustard dressing aside for serving.

When the potatoes have cooked for 20 mins, remove them from the oven. Use the bottom of a bowl or pan to lightly crush each potato.
Drizzle the smashed potatoes with more oil, and return to the top shelf of your oven until crispy and golden, 10-15 mins.

Meanwhile, pop the Serrano ham onto another baking tray and bake on the middle shelf of your oven until crisp and golden, 5-7 mins, then set aside.

Add the lettuce and pear pieces to mustard dressing, then stir through the walnuts and smashed potatoes. Share the salad between your bowls.
Snap the Serrano into shards and serve on top along with a sprinkle of blue cheese. Enjoy!