In a medium mixing bowl, whisk together the buckwheat flour and eggs. Gently add the milk and whisk until smooth. Set the batter aside in the fridge for 20 minutes.
Meanwhile, heat 1 tablespoon of olive oil in a large skillet. Saute the leeks and scallions until soft, about 3 to 5 minutes. Add the spinach one handful at a time - as the greens cook down, you can fit more in the pan. Cook the spinach, tossing constantly, until fully wilted and soft, about 3 minutes. Remove greens to a bowl. Set aside.
Place a small (8-inch) nonstick skillet over medium heat. Add a scant ¼ cup batter to the pan and swirl until the bottom is fully coated. Cook for 30 seconds, then slide your spatula along the edges to loosen the crepe. Cook for 30 seconds more, then flip the crepe. Cook another 30 seconds on the second side, the sprinkle 2 tablespoons cheese over the top of the crepe, followed by two tablespoons greens. Fold the sides of the crepe in to seal the mixture. Slice the completed crepe onto a baking sheet. Repeat with the remaining crepes.
If not serving right away, or the cheese has not fully melted, warm the pan in a 350 degree oven for 5 minutes, or until ready to eat. A nice side salad is a great compliment.
Serves 4 - Makes 8 crepes.