Portobello, Eggplant, and Roasted Red Pepper Panini

Preheat the oven's broiler and set the oven rack at about 6 inches from the heat source. Line a baking sheet with aluminum foil.

Cut peppers in half from top to bottom; remove the stem, seeds, and ribs, then place the peppers cut-sides down onto the prepared baking sheet.

Cook peppers under the preheated broiler until the skin has blackened and blistered, about 5 minutes.

While peppers are cooking, place portobello mushroom caps into a resealable plastic bag. Pour in balsamic vinaigrette, squeeze out excess air, and seal. Marinate in the refrigerator, 8 hours to overnight.

Remove blackened peppers from the oven, transfer to a bowl, and cover tightly with plastic wrap. Allow peppers to steam as they cool, about 20 minutes. Once cool, remove and discard skins. Refrigerate 8 hours to overnight.

The following day, preheat an electric double-sided grill (such as George Foreman®) according to manufacturers' directions. Sprinkle eggplant slices with garlic powder and onion powder.

Remove portobello mushrooms from the marinade, and discard the remaining marinade. Cook on the preheated grill until tender, 4 to 5 minutes. Cook eggplant slices on the preheated grill until tender, 4 to 5 minutes. Remove, set onto a plate, and sprinkle with Parmesan cheese. Set aside.

To assemble the sandwiches, spread all 8 slices of focaccia bread with a thin layer of ranch dressing. Layer 1/2 of the bread slices with a slice of Swiss cheese, an eggplant slice, a roasted pepper half, a portobello mushroom cap, and a slice of Asiago cheese. Top with the remaining bread.

Spray the double-sided grill with cooking spray, and cook the sandwiches until the cheese has melted, the sandwiches are hot in the center, and the bread is golden brown, 4 to 5 minutes.