Boil the potatoes: Put the peeled potatoes into a large pan with enough cold water to cover them, then bring to the boil. Reduce the heat and simmer for 15 to 20 minutes until tender when pierced with a knife.
Infuse the cream: Meanwhile, heat the milk and cream together in a small pan until small bubbles appear around the edge. Remove from the heat, stir in the crushed garlic, and leave to infuse for about 5 minutes.
Rice the potatoes: Drain the potatoes well, then push through a ricer or mouli back into the pan. You can also use a potato masher, but never a food processor or the mash will turn gluey.
Beat in the butter: Add the butter to the warm mashed potatoes and beat until fully combined.
Add the cream: Pour the garlic-infused milk and cream mixture over the mash and mix well. Season to taste with salt and warm through gently over low heat before serving.
