Preheat the oven to 375 degrees. Slice the zucchini into spears, halve the cherry tomatoes, roughly chop the bell pepper, and cut the onion into strips. Creating various shapes makes for fun eating! Place the veggies on a rimmed baking sheet and drizzle lightly with olive oil, and salt and pepper, tossing with your hands to coat. Bake for 15 minutes.
Once the veggies are done, place the baking sheet on a cooling rack. Increase the oven temperature to 425 degrees. Crack the eggs into a medium mixing bowl and whisk. Add in the yogurt, salt, and pepper, and whisk vigorously to combine.
Butter a cast iron skillet VERY well. Slice the cooked veggies into thin strips or chunks and layer in the skillet. Gently pour in the egg mixture. Add a few dollops of pesto and cream cheese throughout the dish.
Bake for about 20 minutes, until the frittata is puffed, pulling away from the sides of the skillet, and the edges are turning a light, golden brown.
Let cool for 5 minutes before serving. The frittata can be enjoyed hot, or at room temperature topped with micro greens for a little pop of color and texture. Store any leftovers in an airtight container in the fridge.