Heat each tortilla in warmed skillet or microwave oven 15 to 20 seconds to soften. Press each tortilla into 10-ounce custard cup, forming a shell. Microwave uncovered on High 2 to 3 minutes, rotating cups 1/2 turn after 2 minutes, until tortillas feel dry. Remove from cups.
Place chocolate chips and shortening in small bowl. Microwave uncovered on High 1 to 2 minutes or until softened; stir until smooth. Dip edges of tortillas into melted chocolate. Drizzle remaining chocolate on inside of tortillas. Refrigerate about 10 minutes or until chocolate is firm.
Mix blueberries and nectarines; spoon into tortillas. Top with yogurt.