In a small skillet, cook beef and onion over medium heat until beef is no longer pink and onion is tender, 5-7 minutes, breaking up beef into crumbles; drain. Stir in cheeses, corn, tomatoes, taco seasoning, jalapeno and the chipotle pepper; set aside., Preheat oven to 375°. Place 1 sheet phyllo dough on a work surface; brush lightly with butter. Cover with another sheet of phyllo; brush with butter. (Keep remaining phyllo covered with a damp towel to prevent it from drying out.) , Cut the 2 layered sheets into three 14x3-in. strips. Place 1 tablespoon filling about 1 inch from corner of each strip. Fold 1 corner of dough over filling, forming a triangle. Fold triangle over, forming another triangle. Continue folding, like a flag, until you reach the end of the strip. Brush end of dough with butter and press onto triangle to seal. Turn triangle and brush top with butter. Repeat with remaining phyllo and filling., Place triangles on greased baking sheets. Bake until golden brown, 12-15 minutes. Combine ranch dressing and salsa; serve with triangles.