Slice eggplant, yellow squash and zucchini into thin rounds – about ⅛ inch thick. Cut the pepper in half lengthwise and then cut into thin slices.
In a small saucepan, heat a teaspoon of olive oil and add some chopped onion. Cook for 3-5 minutes until onion begins to appear translucent. Add garlic and stir for 30 seconds, then add tomato paste and broth or water. Stir until smooth. Remove from heat and let cool slightly.
Prepare baking pan by spraying lightly with cooking spray. Add the sauce and spread evenly in the bottom of the pan.
Arrange slices of eggplant, yellow squash and zucchini to fit the pan in whatever pattern desired. Us the red pepper to insert in between the slices.
When all vegetables are arranged in the pan, drizzle lightly with olive oil. Season with some salt and pepper and sprinkle thyme leaves over the top.
Cut a piece of parchment paper to fit over the vegetables. Use the paper to loosely cover the vegetable.
Bake for 45 minutes at 375F.
Allow to rest for 10 minutes before serving.
Notes
Note: this does not produce a lot of sauce, such as for pasta. If sauce is desired, I recommend preparing it separately.