The Recipe Community is a great resource if you’re looking for tried and tested recipes with reviews.  I lost my Mashed Potato recipe, (I must stop using scraps of paper!) so did a search and found ThermoMike’s great recipe.
However, I wasn’t keen on the large amount that his recipe calls for, so I tweaked it to suit us.

This recipe was developed in the TM6. It’s suitable for the TM31 and the TM5.

Mashed Potato

400g potatoes, peeled and cut into 2cm cubes
500 g water
pinch salt,
1 tsp vegetable stock concentrate
30g Butter
80g Milk

Add potatoes to steaming basket and add the water to the bowl. Cook for 20 mins/Varoma/Stir setting.
Check that the potatoes are nice and soft.
Remove basket and discard the water.
Attach the butterfly and add potatoes back into bowl.
Add veggie stock, milk and butter.
Mix 10 seconds/speed 4. Repeat.

Keep warm in Thermoserver until needed.
Serves 3 or so.
The other alternative recipe that I like is this one on Cookidoo: Mashed Potatoes for Two