Buckwheat crepes are a staple in Brittany, France and eaten at all times of the day. This one is perfect for breakfast paired with some jam or equally lovely as lunch served with a well-dressed mustardy salad.
Preheat the oven to 325 degrees F and lightly grease 2 baking sheets with butter.
Add the milk, granulated sugar, 2 of the eggs and 1/4 teaspoon salt to a blender and blend until smooth. Add the all-purpose flour, buckwheat flour and 2 tablespoons of the butter and blend until smooth, about 1 minute. Transfer the mixture to a bowl. (See Cook’s Note.)
Heat a 12-inch nonstick skillet over medium heat. Brush with butter, add 1/2 cup of the batter and tilt the skillet to swirl the batter evenly over the skillet. Cook until the bottom of the crepe is firm and the edges lift from the skillet, about 2 minutes. Flip and cook until the other side is firm, about 30 seconds. Transfer to a plate and cover with a paper towel. Repeat with the remaining batter, brushing the skillet with butter each time. Wipe out the skillet after the last crepe and reserve for later use.
Transfer a crepe to a work surface and top with 1/2 cup of the cheese, leaving a 1 1/2-inch border all the way around. Top with 2 slices of ham. Fold the top and bottom borders in toward the center, pressing the crepe into the ham so that it sticks. Repeat with the right and left borders to create a square. Transfer the crepe to one of the prepared baking sheets using a spatula. Repeat with remaining crepes, cheese, and ham. Bake until the crepes are warm and the cheese is melted, about 10 minutes.
Meanwhile, heat the remaining butter in the reserved skillet over medium heat. Crack the remaining 6 eggs into the skillet. Cook until the whites are set but the yolks are still runny, about 4 minutes.
Top each crepe with a fried egg. Sprinkle with chives before serving, or sprinkle with confectioners' sugar and serve with red currant jelly.
Ideally, crepe batter should be refrigerated for an hour before cooking but can be used immediately if needed.