Place potatoes in a large saucepan; cover with water. Bring to boil, cover, and then simmer until a wooden or metal skewer inserted into the potato easily slips out, about 20 minutes.
Reserving ¼ cup of the potato cooking liquid, drain potatoes and slash them in half with a paring knife; add oil, garlic, basil, and a generous sprinkling of salt and pepper. Roughly crush potatoes with a fork, adding reserved potato cooking liquid if necessary. Adjust seasonings and serve.
Notes
If you’ve got it, a little chopped fresh parsley is a nice addition to the basil.
Recipe by Three Many Cooks at https://threemanycooks.com/recipes/salads-and-sides/olive-oil-mashed-potatoes-with-garlic-and-basil/