Combine butter and cream cheese in a large bowl until well blended. I like to use my hands, but you can also use a wooden spoon. Mix in flour, 1 cup at a time. As dough becomes stiff, turn out onto the counter; knead in flour until no longer sticky. Continue to knead dough for 5 minutes.

Preheat the oven to 350 degrees F (175 degrees C).

Pulse walnuts in the bowl of a food processor to a fine consistency. Pulse in honey and egg. Set aside.

Transfer dough to a well-floured surface; roll out to 1/4-inch thick. Cut dough into 3x3-inch squares. Place 1 teaspoon filling in center of each square. Use walnut for some and poppyseed for the rest. Roll squares up and seal the edges. These can also be formed into triangles. Place cookies 2 inches apart onto ungreased cookie sheets. Brush with egg white.

Bake in the preheated oven until lightly browned, 15 to 17 minutes. When cool, dust with confectioners’ sugar.