Preheat your oven to 375 degrees Fahrenheit and line a baking sheet with parchment paper.
Add the flour, sugar, baking powder and salt to a large bowl and whisk together with a fork or a whisk until combined.
Add the whole milk to a liquid measuring cup along with the egg and whisk with a fork to combine. Set aside.
The next few steps should be done quickly, as you're working with cold butter and you want the butter to be as cold as possible when it hits the heat of the oven. This will result in a flaky scone, rather than a heavy and dense one.
Cut up your butter, right from the fridge, into little pieces and dump it into the flour mixture. Using your hands (wash them well first and remove any rings), pick up handfuls of the butter and flour mixture, rubbing the pieces of butter and the flour between the heels of your hands to create "sheets" of butter. You should act quickly here, and don't allow the pieces of butter to sit in your hands for any length of time as the heat from your hands will cause it to soften. The goal is to create paper-thin pieces of butter, small and large throughout the mixture.
Once there are no thick chunks of butter remaining, only thin sheets, remove your hands from the mixture. Hands equal heat, so handle the mixture as little as possible.Pour in the wet ingredients and mix roughly with a fork. Do not over mix, or the result will be heavy and dense.
Once the wet ingredients have been incorporated but there are still several streaks of flour, turn the dough out onto a clean and floured counter surface. Press the dough down into the counter and add a handful of chocolate chips onto the surface of the dough. Then fold one half over the other half like you are folding a piece of paper. Add more chocolate chips, press down again and make another fold.
Repeat this 2 or 3 more times, adding all the chocolate chips as you go, gathering any outlying dough bits and flour into your folds. Don't knead the dough like you would if you were making bread, and don't stir or mix the dough like you would if you were making muffins. Scones are technically a pastry, so the goal is flaky layers that are created by the thin sheets of butter and all the folding.
Once your dough is formed after folding several times, shape it into a rectangle about 20-30 cm long.Again, be careful not to handle the dough too much, so a few little cracks here and there are fine.
Cut the rectangle into 10 triangles by making diagonal slices across the rectangle with a very sharp knife. Arrange the 10 triangles on the prepared parchment-lined baking sheet and brush the tops with a little bit of whole milk.
Bake for about 18-19 minutes at 375 degrees Fahrenheit. I usually set the timer and start watching them after about 14 minutes. You want them to stay nice and white and not get too brown, especially on the narrow end of the triangle.
Remove them from the oven when they're just barely golden brown on the bottom and the surface of the scones have lost their shine. Let them cool for 3-5 minutes on the baking sheet. Transfer them to a cooling rack to cool completely.