Make the sauce base

• Heat olive oil in a pan and soften the diced onion and bell pepper.
• Add the garlic and cook until fragrant.
• Stir in the crushed tomatoes, salt, pepper and thyme, then simmer until thickened.

Slice the vegetables

• Slice the eggplant, zucchini, yellow squash and tomatoes into thin, even rounds.
• Spread the sauce base evenly over the bottom of a baking dish.

Arrange the ratatouille

• Layer the vegetable slices upright in alternating spirals over the sauce.
• Drizzle with olive oil and season with salt, pepper and thyme.

Bake

• Cover with parchment and bake until the vegetables are tender.
• Uncover and bake a little longer to lightly brown the top.

Serve

• Let the ratatouille rest briefly before slicing and serving.