1. Heat a large skillet over medium-high heat. Coat pan with cooking spray. Add 1/4 cup onions, Italian seasoning, 1/4 teaspoon salt, fennel, and garlic; sauté 6 minutes or until pork is done, stirring to crumble. Remove from heat; cool slightly.
2. Combine remaining onions (about 1 1/3 tablespoons), remaining 1/4 teaspoon salt, milk, and next 5 ingredients (through red pepper) in a large bowl; stir with a whisk. Add pork mixture, 1/2 cup cheese, and bread; stir to combine. Pour into an 11 x 7-inch glass or ceramic baking dish coated with cooking spray. Cover and refrigerate 8 hours or overnight.
3. Preheat oven to 350°.
4. Uncover dish; let stand at room temperature 20 minutes. Sprinkle with remaining 1/4 cup cheese. Bake at 350° for 50 minutes or until set and lightly browned. Let stand 10 minutes before serving.