Florentine Brunch Casserole

16 slices firm white bread
3 tablespoons butter or margarine, divided
1 can (10 3/4 ounces) condensed cream of celery soup
1/3 cup milk1/4 teaspoon coarsely ground black pepper
1/3 cup onion, chopped
4 ounces baked ham, diced (about 1/2 cup)
1 red bell pepper, diced (about 1 cup)
10 eggs, lightly beaten
4 ounces cheddar cheese, shredded, divided (1 cup)
1 bag (5 ounces) fresh spinach leaves, washed and stemmed

Preheat oven to 375ºF. Cut crusts off bread; cube crusts and measure 2 cups. Arrange bread slices in an overlapping pattern against sides of a oval baker; place bread cubes in bottom. Microwave 2tablespoons of the butter in small microwave-cooker on HIGH 30 seconds or until melted; lightly brush over bread slices using Pastry Brush. Bake 15-20 minutes or until edges of bread are golden brown. Meanwhile, in a bowl, whisk soup, milk and black pepper until smooth. Finely chop onion using a chopper. Dice ham and bell pepper. Melt remaining butter in a stir-fry skillet over medium heat; add onion and bell pepper. Cook 5 minutes or until vegetables are tender; stir in ham. Whisk eggs; add to skillet. Cook over medium-high heat, stirring occasionally, until eggs are set but still moist. Stir in soup mixture; cook 1 minute or until hot. Grate cheese. Gently stir in 3/4 cup of the cheese. Fold spinach into egg mixture, half at a time. Cook about 2 minutes, stirring gently until spinach is wilted. Spoon egg mixture into center of baker, mounding slightly in center. Top with remaining 1/4 cup cheese. Serve immediately