Preheat the oven to 180°C (350°F). Lightly grease a baking dish or line with parchment paper.
Bring a pot of salted water to a boil. Blanch the cauliflower and broccoli florets for 2–3 minutes until slightly tender but still crisp. Drain and rinse under cold water to stop the cooking.
Layer the blanched cauliflower and broccoli in the prepared baking dish. Scatter diced sweet pepper and cherry tomatoes evenly over the top.
In a separate bowl, whisk the eggs and heavy cream together until smooth. Season with salt, black pepper, and dried oregano.
Pour the egg mixture evenly over the vegetables in the baking dish.
Bake in the preheated oven for 30–35 minutes, or until the top is golden and the center is set.
Let cool slightly before slicing and serving.