Pre-heat your oven to 350 degrees Fahrenheit.
Bring the oil to medium heat in an 8”-10” oven-safe skillet over medium heat. Add the broccoli and zucchini and stir to coat. Sprinkle with a bit of salt and pepper to taste. Cook, stirring regularly, for about 4 minutes until the broccoli is bright green and tender*. Add the chopped spinach and stir together. Continue to cook for an additional 2 minutes until wilted.
*While the vegetables are cooking, break the eggs into a large mixing bowl and whisk together until just combined. Add the yogurt, chives, salt, black pepper, thyme and Feta and stir together until mixed.
When the vegetables are cooked, transfer them into the bowl containing the egg mixture and stir together. Spray the skillet you used liberally with cooking spray and then pour the egg mixture into the skillet. Cook on a burner set to medium heat for 5-7 minutes until the very outside edge of the frittata starts to turn opaque/look cooked. Transfer the skillet into the oven and cook for 15-20 minutes until the center is set. Let cool for 5 minutes, then slice into 6 slices and serve.