Preheat oven to 200 degrees; have a baking sheet or heatproof platter ready to keep cooked pancakes warm in the oven. In a small bowl, whisk together flour, sugar, baking powder, and salt; set aside.
In a medium bowl, whisk together milk, butter (or oil), and egg. Add dry ingredients to milk mixture; whisk until just moistened (do not overmix; a few small lumps are fine).
Heat a large skillet (nonstick or cast-iron) or griddle over medium. Fold a sheet of paper towel in half, and moisten with oil; carefully rub skillet with oiled paper towel.
For each pancake, spoon 2 to 3 tablespoons of batter onto skillet, using the back of the spoon to spread batter into a round (you should be able to fit 2 to 3 in a large skillet).
Cook until surface of pancakes have some bubbles and a few have burst, 1 to 2 minutes. Flip carefully with a thin spatula, and cook until browned on the underside, 1 to 2 minutes more. Transfer to a baking sheet or platter; cover loosely with aluminum foil, and keep warm in oven. Continue with more oil and remaining batter. (You'll have 12 to 15 pancakes.) Serve warm, with desired toppings.