Once you have poured the buckwheat batter onto the crepe pan, add the cheese, leaving a circle of cheese with the middle clear.
Pour the egg in the clear circle.
Cook until the cheese melts and the egg sets.
Add the spinach on top of the egg, then the dollop of sour cream.
Cook for a few minutes.
Fold the 4 sides of the galette over forming a rough square. Leave the middle open for a more pleasing presentation.
Serve.
Notes
*I like my eggs cooked so I beat the egg and then add it to the filling. The classic egg galette bretonne is with a sunside egg peaking out from the folded crepe. For a picture of the classic egg placement see below.