- 1 tablespoon olive oil
- 1 large leek (white and light green parts only), cleaned and sliced into half-moons
- 1 large shallot, minced
- 1/2 teaspoon salt
- 1/2 cup Greek yogurt (any fat percentage)
- 1/4 cup chicken or vegetable broth
- 1 medium zucchini, thinly sliced into rounds
- 1 medium yellow squash, thinly sliced into rounds
- 2 large tomatoes, thinly sliced into rounds
- 2 large ears of corn, kernels only
- 1/2 pound green beans, trimmed and cut into bite-size pieces
- 1/3 cup panko breadcrumbs
- 1 tablespoon finely grated Parmesan or pecorino cheese
Pro tip: to quickly slice vegetables (and even tomatoes!), a handheld Japanese slicer is an inexpensive and worthwhile kitchen investment.
Preheat the oven to 375 degrees F.
Heat the olive oil in a large skillet over medium heat. Stir in the leek, shallot and salt. Cook, stirring occasionally, for about 5 minutes until the leek is starting to soften, then cover and continue to cook for about 5 minutes more until the leek is very soft. Remove from the heat and transfer to a bowl. Stir in the yogurt and broth. Assemble the casserole: Line a 9-inch round or square casserole dish with a layer of zucchini and yellow squash, alternating rounds if desired for a colorful presentation. Top with a layer of tomato slices, then half the corn and half the green beans.
Spoon half the leek and yogurt mixture evenly over the vegetables, then repeat with the remaining vegetables and leek/yogurt mixture for a second layer. The top layer may rise slightly higher than the top of the casserole dish; it will sink slightly as the vegetables cook.
Stir the panko and Parmesan together in a small bowl, then sprinkle evenly over the top of the casserole.
Cover the casserole loosely with foil and cook for 30 minutes, then remove the foil and cook for 15-20 minutes more to toast the panko topping.