Add 1 teaspoon butter to pan; pour 1/4 cup egg mixture in center of pan. Do not stir. Cook until almost set; turn egg, and cook 30 seconds.
Remove from heat, and keep warm. Repeat with remaining butter and egg mixture.
Spread 1 tablespoon Toasted Mustard Seed Aoli on bottom half of each bagel; add cooked egg, and top each evenly with tomato and spinach. Top with remaining bagel half.