Simple. Crush one small clove of garlic per large potato and add to the water. Boil as normal, then mash with a knob of butter. Alternatively, instead of he butter, mash in a small tub of Philadelphia...
Put whole peeled garlic cloves into the pan with the potatoes (I normally do about 3) and a stick of celery, then boil as usual. When done, throw the celery out, and mash the potatoes and garlic up with butter or olive oil. The celery really does make a difference - try it!
I find most of the flavour of the garlic cooks out into the water and is lost when drained. I use a steamer over the pan of spuds to cook it . Then add garlic to spuds after draining - then mash with olive oil - Healthier than butter.
Just new to this site but I love garlic mash!! I cut a large bulb in half (horizontal), drizzle with a little olive oil, salt and pepper and roast in the oven for 20 minutes 190'c. Then squeeze out the garlic into your potato and mash away!