Preheat oven to 350° (180°C). Spray 9-inch (23 cm) quiche dish or pie plate with non-stick cooking spray; set aside.
Heat oil in large skillet over medium-high heat and cook asparagus, yellow bell pepper and onion, stirring occasionally, 3 minutes or until crisp-tender. Evenly spread vegetable mixture in prepared dish.
Beat eggs, 1/2 cup (125 mL) milk, salt and pepper in bowl. Evenly pour over vegetables. Bake 25 minutes or until set.
Prepare Knorr® Hollandaise Classic Sauce Mix with margarine and remaining 1 cup milk according to package directions. Serve Hollandaise over omelette.
SUBSTITUTION: Use 1 pkg. Knorr® Béarnaise Classic Sauce Mix instead of Knorr® Hollandaise Classic Sauce Mix.