1. Preheat oven to 400°.
2. Combine first 5 ingredients, stirring well. Stir in egg whites, milk, and vanilla.
3. Coat a baking sheet with cooking spray. Using your finger, draw 4 (5-inch) circles on baking sheet. Spoon 1 tablespoon batter onto each circle, spreading to edges of circle using the back of a spoon. Bake at 400° for 6 minutes or until edges begin to brown. Loosen edges with a spatula; remove from baking sheet. Working quickly, gently drape each taco over suspended wooden spoons, gently shaping into a shell; cool completely. (Shells are delicate and should be handled carefully when shaped.) Repeat procedure to form a total of 8 shells.
4. Combine chocolate chips and oil in a microwave-safe bowl. Microwave at HIGH 1 minute or until chocolate melts, stirring after 30 seconds; stir until smooth. Gently spread about 1 teaspoon chocolate mixture on the top third of the outside of both sides of cooled shells, and sprinkle with about 1 teaspoon chopped peanuts. Spoon 1/3 cup ice cream into each shell. Drizzle remaining chocolate mixture evenly over ice cream; sprinkle evenly with remaining peanuts. Freeze for at least 30 minutes before serving.