Substitute pasilla chiles
A decent second choice: Pasilla powder. Pasilla powder is made from chilaca peppers. When dried, chilaca are called pasilla negro chilies because of their dark brown color. The word pasilla comes from pasa, which means small black raisin. Pasilla negro chilies have a similar heat level to the poblanos used to make ancho powder.A long, slend, dark dried chile. Mexican Pasilla chiles have an earthy flavor and are used in mole sauce as well as other Mexican sauces and stews (chile negro). In California the ancho chile is called pasilla but that is a completely different chile. substitute pasilla chiles
The closest in flavor: Pasilla pepper. Pasilla peppers (a. k. a. chile negro) are also a member of the Holy Trinity of Mexican chilies. They have a comparable heat to ancho peppers, but can reach the level of guajillos at their hottest (1, 000 to 2, 500 SHU).