1Heat oven to 425°. Cut butter and 3-ounce package of cream cheese into Bisquick mix in medium bowl, using pastry blender or crisscrossing 2 knives, until mixture looks like fine crumbs. Stir in milk and egg yolk. Place dough on surface well dusted with Bisquick mix; gently roll in Bisquick mix to coat. Shape into a ball; knead 10 times.
2Roll dough into 16x8-inch rectangle. Spread chive-and-onion cream cheese lengthwise over half of dough to within 1/4 inch of edges; sprinkle with Gouda cheese. Carefully fold dough over filling. Brush egg white over top; sprinkle with parsley. Cut into four 4-inch squares; cut squares diagonally in half to form 8 triangles. Place on ungreased cookie sheet.
3Bake 10 to 13 minutes or until golden brown. Cut each triangle in half. Serve warm.