Buttermilk Rye Crepes

Blend eggs, egg yolk, buttermilk, and milk in a blender until smooth. Add rye flour, all-purpose flour, salt, and 2 tablespoons sugar and blend well. With blender on low, gradually stream in melted butter. Strain batter through a fine-mesh sieve into a large measuring cup or medium bowl. Heat 1/2 teaspoon butter in a medium nonstick skillet over medium heat until foamy. Pour 1/4 cup batter into skillet and swirl to coat bottom of pan. Cook crepe until lacy and golden brown on one side, about 2 minutes. Carefully flip crepe and cook on other side until just cooked through, about 1 minute longer; transfer to a plate. Repeat 7 times with remaining batter and stack crepes, placing a piece of parchment paper between each as you go to prevent sticking (you should have about 8 crepes). Just before serving, heat 1 teaspoon butter in a large skillet over medium-high heat. Fold 2 crepes in half and place side by side in skillet; sprinkle with 1 teaspoon sugar total, then flip. Cook until sugar is beginning to caramelize, about 1 minute. Repeat with remaining crepes. Serve with lemons for squeezing over. DO AHEAD: Crepes can be made 2 days ahead. Cover and chill.