Coat twelve, 2 1/2-inch muffin cups with nonstick cooking spray. In a large skillet cook bacon 5 to 7 minutes or until cooked through but still pliable and just starting to brown, turning occasionally. Drain on paper towels; let cool until easy to handle.

Wrap one slice of bacon around the inside of each muffin cup. In a large bowl whisk together eggs, milk, spinach, garlic, cheese, 1/2 teaspoon salt and 1/4 teaspoon black pepper. Divide egg mixture among cups. Cover; chill overnight.

Preheat oven to 375°F. Uncover muffin cups. Top each with a tomato slice. Bake 25 minutes or until eggs are puffed and set. Let cool in cups 5 minutes. (Eggs may fall slightly during cooling). Loosen sides; remove from cups. Serve warm.