HEAT oven to 450°F.
MIX cream cheese spread, milk and seasoning until blended. Meanwhile, heat 2 tsp. oil in large skillet on medium-high heat. Add mushrooms and peppers; cook 4 to 5 min. or until crisp-tender, stirring occasionally. Add spinach; stir. Cook 1 min. or just until wilted. Remove from heat.
PLACE pizza crust on baking sheet; spread with cream cheese mixture. Top with 1/2 cup cheese, cooked vegetables and remaining cheese. Brush edge of crust with remaining oil.
BAKE 12 to 14 min. or until cheese is melted.