To bake bacon to crispy, preheat oven to 400 degrees F. Place bacon slices on a rack set over a baking sheet. Line baking sheet with aluminum foil for easy clean up. Bake bacon for 10 to 14 minutes OR until crispy. Remove from oven and let cool.
Toast bread for more crispy sandwich.
Spread mayonnaise on one side of each slice. Arrange bacon, tomato slices, spinach or lettuce and avocado and assemble sandwiches.