Preheat oven to 350°. Line a rimmed baking sheet with foil.
In a medium skillet, heat 1 tablespoon oil over medium-high heat. Add bell pepper; cook, stirring frequently, until just soft, about 3 minutes. Remove from heat; stir in dressing and egg white.
Place mushrooms on prepared pan; brush with remaining 1½ tablespoons oil, and sprinkle with salt and pepper. Spoon dressing mixture into mushroom caps.
Bake for 15 minutes. Sprinkle with cheese, and bake until melted, about 5 minutes more. Serve immediately.
Recipe by Paula Deen Magazine at https://pauladeenmagazine.com/dressing-stuffed-portobello-mushrooms-recipe/