Process eggs, milk, melted butter, and salt in a blender until frothy and evenly mixed, 20 to 30 seconds. Add flour, and process until just smooth (do not overmix), about 3 seconds. Transfer to a medium bowl; cover and let rest at room temperature 1 hour or in refrigerator up to 12 hours.

Whisk club soda into batter. Heat a 9- to 10-inch cast-iron crêpe pan or a low-sided skillet over medium. Lightly coat pan with butter.

Pour a scant 1/4 cup batter into prepared crêpe pan, and tilt to coat pan bottom. Cook until lightly browned and sides release easily, 1 to 2 minutes. Flip pancake using a long offset spatula or a large fish spatula, and cook until brown spots appear and pancake releases easily from crêpe pan, about 1 minute. Slide pancake onto a large plate, and keep flat. Repeat with remaining batter, making 11 more pancakes and adding additional butter as needed to grease pan. Stack pancakes on top of each other on plate.

Working with 1 pancake at a time, transfer pancake to a cutting board; spread 1 tablespoon sárgabarack lekvár over each pancake, and roll pancake into a thin cylinder. Serve slightly warm or at room temperature, topped evenly with sliced peaches.