Crêpes: In blender, combine milk and eggs. Add flour and salt and blend at low speed until smooth, less than 1 minute. Let batter stand ½ hour. If you do not have a crêpe pan, place a large cast iron skillet over moderately high heat, brush lightly with melted butter, and heat until butter just begins to smoke. Pour ¼ to ⅓ cup batter into pan, tilting to spread into thin, even layer. Cook until crêpe begins to blister, edges curl slightly away from skillet, and underside is lightly browned, about 1 to 2 minutes. Use flexible spatula to flip crêpe out of skillet and onto plate, cooked side up. Repeat with remaining batter, brushing skillet lightly with melted butter before cooking each crêpe. Stack crêpes, cooked side down, on plate and let cool.

Filling: In large bowl, mash together farmer and cottage cheeses until blended. Add egg yolk, melted butter, sugar, and salt, and mix until combined.

Sauce: In large saucepan, combine concord jam and port wine, stir together and over medium high heat reduce by half. Add butter and emulsify by whisking until medium-thick consistency.

Blintzes: Place 2 tablespoons filling in center of crêpe. Fold up bottom, fold down top, then flip over and fold in sides to cover filling. Place seam side down on a large plate. Repeat with remaining crêpes and filling. Heat 1 tablespoon butter in iron skillet over moderately high heat. Add 3 blintzes and fry until golden brown on both sides, about 1 to 2 minutes per side. Repeat with remaining blintzes. Serve hot with sauce.