Combine apples, sugar, juice and vinegar in 3-quart heavy saucepan; cook until apples start to break down. Reduce heat to low; cook until soft and mixture thickens, stirring occasionally, about 45 minutes. Keep warm.
In small bowl, whisk together the flour, eggs, 1 tablespoon melted butter and milk to form a smooth thin batter. Refrigerate at least 30 minutes. Heat small skillet or crepe pan; brush lightly with butter. Pour scant 1/4 cup batter into pan, tilting and rotating pan to evenly cover bottom in thin layer. Cook about 30 seconds, until golden brown on bottom. Transfer crepe to plate; cover loosely to keep warm. Repeat with remaining batter to yield 8 crepes, placing waxed paper between crepes.
Preheat oven to 350°F.
In medium bowl, combine the mascarpone, blue cheese and black pepper. Divide filling evenly among crepes, spreading over and leaving 1/2 inch uncovered around edge. Fold crepes into quarters to form triangles. Heat remaining 2 tablespoons butter in large heavy sauté pan over medium-high heat. Add crepes in batches, browning on both sides. Place in buttered baking dish and warm in oven 3 to 5 minutes.
Plate 2 crespelle on each plate. Top with apple jam and dust with confectioners’ sugar. Reserve leftover apple jam for additional servings.