In a large bowl whisk together egg, egg white brown sugar, winter squash, olive oil and vanilla extract. Add cocoa powder, whole-wheat flour, salt and chocolate chips and mix until well combined.
Pour batter into an 8-inch square pan coated with cooking spray. Bake at 350ºF until brownies spring back to the touch, 23 to 25 minutes.
Cool, then dust with confectioners' sugar before serving.
•It's a challenge to come up with a nutritious and delicious brownie. Each square has nearly 3 grams of fiber (thanks to whole-wheat flour) and just 2 grams of saturated fat (thanks to olive oil). The magic ingredient? Squash, to make it moist and rich. Done and done!•I use frozen pureed squash in this recipe, but you can swap that for canned pumpkin puree or squash, or mashed sweet potatoes!