Heat the olive oil in a large sauté pan over medium-high heat. Cook the onions and bell pepper until soft, stirring occasionally, about 5 minutes. Season with a little salt and pepper. Transfer to a bowl; set aside.
In a large bowl, whisk together the eggs, half-n-half, and salt. Add in the scallions and parsley.
Butter a 9’’×13’’ baking dish. Scatter half of the bread cubes on the bottom. Sprinkle with 1 1/2 cups of the cheese on top, followed by the onion/bell pepper mixture and ham. Top with the remaining bread. Pour the custard on top; cover with plastic wrap and let stand 30 minutes or refrigerate overnight. (Bring to room temperature before baking.)
Preheat oven to 350°F. Uncover; sprinkle remaining 1/2 cup cheese evenly over the top. Bake for about 50-55 minutes or until puffed and golden and a knife inserted comes out clean. Let rest for 10 minutes before serving. Cut into squares and enjoy!
Copyright of Amy Flanigan, Very Culinary