Sift both flours and salt together in large bowl. Stir in the sugar. At first mix the yeast with only three tablespoons of the water or parve milk; only then add the rest of the water or parve milk to the yeast mixture.

Make a well in the center of the flour and pour the yeast mixture into it. Add the egg and gradually knead or mix until it becomes a soft dough. Knead the dough for three to four minutes longer.

Lightly smear the dough and bowl with oil. Cover and let rise for 45 minutes to one hour or until doubled.

Punch down dough, cover, and place in refrigerator to chill for one hour.

Flatten butter or margarine into a rectangle, 3/4-inch thick.

Punch down dough again, then roll out on a lightly floured surface, forming a 10-inch square, with the edges rolled slightly thinner than the center.

Place the rectangle of butter or margarine in the center of the dough, and fold all four corners of the dough toward the center, to completely cover the butter or margarine. Roll the “dough envelope” into a rectangle, about 3/4-inch thick, twice as long as it is wide. Fold the bottom one-third up and the top one-third down to the center and seal the edges. Wrap in plastic wrap and chill another 20 minutes. Repeat this step, rolling, folding, and chilling, twice more.

Roll out dough onto a floured surface into a 24- x 12-inch rectangle. Cut the rectangle in half lengthwise. Cut each new rectangle into 14 equal triangles. Place dough triangles on two baking sheets. Cover and chill 10 minutes more.

To shape croissants, place each triangle on a floured surface with the wide end on top. Gently stretch the triangle a little to make it more elastic, then roll up from the wide end to the pointed end. Tuck point under. Curve ends to form half-moon shape. Place on two greased or lined baking sheets, spaced well apart.

Preheat oven to 425 degrees Fahrenheit. Combine one egg yolk and one tablespoon water for glaze. Lightly brush over croissants. Cover loosely and let rise in a warm place for about 30 minutes or until almost doubled.

Brush croissants with remaining glaze and bake 15–20 minutes or until crisp and golden. Cool slightly. Serve warm with butter or jam.