Cook peppers and garlic in large skillet sprayed with cooking spray on medium-high heat 2 to 3 min. or until peppers are crisp-tender, stirring frequently. Add spinach; cook and stir 2 to 3 min. or just until spinach is wilted.
Whisk milk and egg product in large bowl until blended. Add spinach mixture and remaining ingredients; mix well.
Pour into 13x9-inch baking dish sprayed with cooking spray.
Bake 45 to 50 min. or until knife inserted in center comes out clean.