Place potatoes in a large pot with enough water to cover potatoes.
Bring to a boil over high heat and cook until potatoes are tender. This should take about 20 minutes.
Drain potatoes into a colander. Return drained potatoes to the large pot.
Add the butter salt, pepper and half of the milk.
Mash potatoes with a masher until smooth, add the remaining milk as you are mashing.
Melt butter in a medium size pot.
Add the flour and stir together constantly with a wooden spoon until flour butter mixture begins to brown.
Slowly add the hot liquid, stir with a wire whisk until all the stock is absorbed and there are no lumps.
Then add the gravy and bring to a boil stirring constantly and simmer for 10 minutes.
Strain gravy and serve with the potatoes.
