Zucchini Burgers with Roasted Garlic Tzatziki

Preheat the oven to 425°. In a large bowl, toss the zucchini and yellow squash with 6 tablespoons of olive oil. Season with salt and pepper and spread on 2 baking sheets in a single layer. Roast until golden, turning the squash and rotating the baking sheets halfway through, 1 hour. Let cool to room temperature.

In a bowl, combine both paprikas with the cayenne, garlic and 1 tablespoon of salt. In a food processor, pulse the squash and zucchini with the paprika spice mix in 2 batches until finely chopped. Transfer to a large bowl. Stir in the panko and parsley and mix gently.

Form the mixture into eight 4-inch burgers about 1 inch thick. Arrange the burgers on a parchment-lined baking sheet and refrigerate for 1 hour.

On a griddle, heat 2 tablespoons of olive oil. Cook the burgers over moderately high heat until well-browned and heated through, 5 to 7 minutes per side. Set the zucchini burgers on the rolls and serve with the toppings.