Start by frying the bacon until crispy, but not too crisp. You can do this in a frying pan, air fryer, or oven. I personally prefer baking the bacon in the oven for easier clean up, especially if I am making enough for 3 or 4 blt's at the same time. Once the bacon is crispy, transfer it to a paper towel-lined plate. Keep warm until you are ready to assemble the sandwich.
4 slices bacon
Wash and dry the lettuce so it is crisp and cold for the sandwich. Slice the tomato into slices that are about 3/8-inch thick. Place on a plate and sprinkle with coarse kosher salt and freshly ground black pepper. Drizzle with a little olive oil and vinegar. Let sit while preparing the rest of the sandwich ingredients so the salt can draw out some of the tomato juices so they don't make the sandwich too soggy.
2-4 pieces green leaf lettuce, 1 ripe heirloom or garden fresh tomato, Coarse kosher salt, Freshly ground black pepper, 1-2 teaspoons olive oil, 1-2 teaspoons red wine vinegar
While the bacon cooks, butter both sides of the bread with the softened butter. Lightly toast the bread in a large skillet over medium heat until golden brown on both sides, then set aside.
2 slices hearty white bread, 4 teaspoons salted butter
To assemble the sandwich, spread about 1 1/2 Tablespoons of the mayo or garlic aioli onto one side of the toasted bread. Top with the crisp lettuce and layer on the sliced tomato. Sprinkle with additional coarse kosher salt and pepper, if needed. Pile on the crispy bacon strips, breaking them in half so they all fit on the sandwich, if necessary. Top with a slice of pepperjack or havarti cheese and the sliced avocado, if using.
3 Tablespoons mayonnaise, 1 slice pepperjack or havarti cheese, 1/2 ripe avocado
Spread the remaining 1 1/2 Tablespoons of mayo on the other piece of toasted bread and use it to top the sandwich. Use a sharp knife to cut the sandwich in half and enjoy immediately!