Preheat oven to 375°F. Heat oil in a large skillet over medium. Add onion and bell pepper and sauté until softened, about 10 minutes. Add garlic and cook until fragrant, about 2 minutes.
The feta and bread are optional and can be omitted to make the recipe dairy-free or gluten-free. I've made it without the feta and eaten it without bread and it's fantastic!
Be SO SO CAREFUL not to touch the handle of the pan after you take it out of the oven - it's so easy to forget that it just came out of the oven and then grab it & burn your hand. I recommend keeping the handle covered with a kitchen towel or potholder after you take it out.
Adapted from Cooking Light