Heat the oven to 325°. Brush an 8-inch nonstick skillet with softened butter. Pour in 1/4 cup of the batter and tilt to coat. Cook for 45 seconds over moderately high heat. Turn and cook for 10 seconds longer. Transfer to a plate. Repeat with the remaining butter and batter, reducing the heat to moderate when the pan becomes too hot; stack the crêpes. Spread 1 scant tablespoon of dulce de leche on each crêpe and fold in quarters. Arrange the crêpes, overlapping, on 2 baking sheets and bake for about 5 minutes, or until warmed through. Transfer to a platter, dust with confectioners’ sugar and serve.