1Spray 10-inch skillet with cooking spray; heat over medium heat. Cook broccoli and mushrooms in skillet about 5 minutes, stirring occasionally, until broccoli is crisp-tender.
2Melt margarine in 1-quart saucepan over low heat. Stir in flour, salt and garlic. Cook over low heat, stirring constantly, until mixture is smooth and bubbly; remove from heat. Mix milk and egg yolk until smooth; stir into flour mixture. Heat to boiling, stirring constantly. Boil and stir 1 minute. Stir in broccoli mixture; remove from heat.
3Cut 2-inch hole in center of each slice toast. Spray same skillet with cooking spray; heat over medium heat. Place 1 slice toast in hot skillet; crack 1 egg into hole in toast. Cook until egg white and yolk are firm, not runny. Remove from skillet; keep warm.
4Repeat with remaining toast and eggs. Top with broccoli mixture. Sprinkle with sesame seed. Serve immediately.