1Heat oven to 425º. Remove stems from mushrooms; thinly slice mushrooms.
2Heat oil in 10-inch nonstick skillet over medium-high heat. Cook bell peppers in oil 2 minutes, stirring occasionally. Stir in mushrooms, marjoram and salt. Cook 1 to 2 minutes, stirring constantly, until mushrooms are just tender.
3Place pizza crust on ungreased cookie sheet. Spread mushroom mixture over crust. Top with cheese.
4Bake 8 to 10 minutes or until hot and cheese is melted. Cut into thin wedges to serve.