In a large pot of water, place the fingerling potatoes and bring to a boil. Turn heat down to simmer and cook until then can be pierced easily with a fork. (Total time should take about 30 minutes. Be careful to not overcook them.) Drain and set the drained potatoes on a double layer of paper towels to cool.
Using a clean dishtowel or paper towel, gently smash the potatoes with the bottom of a glass and place on baking sheet. (The potatoes can be prepared to this point up to 8 hours ahead of time. Let cool completely before refrigerating)
Preheat oven to 450 degrees.
Season potatoes with salt and pepper and drizzle olive oil, making sure that a bit of oil gets under each potato so they are entirely coated. Roast for 30-40 minutes, flipping once with a spatula half way through. Roast until edges are crispy and brown. Serve immediately.