Everything about these sandwiches screams "backyard summer party" to me. Simmering vegetables all day really brings out the individual flavors, and I love how I can get so many good-for-you vitamins into such a delicious package.

Ingredients

　　1 eggplant, peeled, quartered, and sliced

　　1 red onion, sliced into thin rings

　　1 red bell pepper, seeded and thinly sliced

　　1 orange bell pepper, seeded and thinly sliced

　　1 medium zucchini, thinly sliced

　　2 small yellow summer squash, thinly sliced

　　3 ripe tomatoes, quartered

　　1/4 cup prepared pasta sauce

　　1 tablespoon olive oil

　　1/2 teaspoon kosher salt

　　1/4 teaspoon ground black pepper

　　8 soft sandwich buns, toasted

　　8 ounces Swiss or provolone cheese, sliced (optional)

　　Use a 6-quart slow cooker. Put the eggplant, onion, bell peppers, zucchini, squash, and tomatoes into the insert. Add the pasta sauce, oil, salt, and black pepper, and stir well to combine. Cover, and cook on low for 8 hours, or until the vegetables have broken down quite a bit and the onion is translucent. Serve on the buns with a slice of cheese on top, if desired.

　　Excerpted from 365 Slow Cooker Suppers © 2013 by Stephanie O'Dea. Reproduced by permission of Houghton Mifflin Harcourt. All rights reserved.