Prepare the Veggies: Heat the olive oil in a large, oven-safe skillet or slow cooker over medium heat. Add the chopped onion, zucchini, and bell pepper. Sauté for 5-7 minutes until the vegetables are softened and slightly golden.

1. Add the Tomatoes: Add the cherry tomatoes to the skillet and cook for an additional 2-3 minutes, until the tomatoes start to soften and release their juices.
2. Prepare the Egg Mixture: In a large bowl, whisk together the eggs, milk (or cream), dried thyme, dried rosemary, salt, and pepper until well combined. Stir in the grated cheese.
3. Combine and Cook: Pour the egg mixture over the sautéed vegetables in the skillet. Reduce the heat to low and cover the skillet. Cook for 15-20 minutes, or until the eggs are set but still slightly soft in the center. If you’re using a slow cooker, set it on low for 2-3 hours, or until the eggs are fully cooked.
4. Finish and Serve: Once the frittata is cooked through, remove from heat. Garnish with freshly chopped basil or parsley for a burst of color and flavor.
5. Serve: Slice and serve the frittata warm. It’s perfect with a side of mixed greens or crusty bread.