Arrange bacon slices on a wire rack inside a baking pan lined with aluminum sheet to catch the grease. Brush the bacon slices with maple syrup on 1 or both sides depending on how sweet you want it to be. Bake in the preheated to 180C/350F oven for 20 minutes until the fat is rendered and the bacon is crispy.
Mix the mayonnaise with the chipotle paste and garlic, then set aside to infuse.
Spread the butter on one side of each slice of bread and toast it on a pan. If you wish to use a toaster instead, toast the bread first, then spread the butter on it.
After the bread has been toasted, spread the chipotle mayo on one side of the bread slice. Assemble your BLT by layering the lettuce and tomato slices, then bacon and sliced avocado. Top with the second slice of bread toasted side up.