Beat the eggs in a mixing bowl, add the grated cheese, salt and freshly ground pepper. Then fold in the basil leaves, tearing the larger leaves into pieces.

Heat a skillet (non-stick or seasoned carbon steel, see Notes below) and cover the bottom with olive oil. Add the egg mixture into the hot oil and proceed following the usual technique for making a frittata, frying one side until lightly golden brown, then flipping the frittata over and browning the other side, until cooked through, about 5 minutes per side. 

Slide the frittata onto a serving plate. Let it cool a bit (or entirely) before slicing and serving.