You can skip the bacon part if you prefer to cook bacon another way. The oven gives you an option to cook a whole package at once, but you may need 2 sheet pans.

Oven-baked bacon: line a sheet pan with aluminum foil. I typically overlap two or three pieces of foil. You probably can't get a whole package of bacon on one pan, so you might need an addition oven safe pan if you want to cook the whole package. 

Remove the bacon from the package and lay as many slices as you can on the foil-lined baking sheet. You can place your bacon very close together, but try not to overlap the pieces. If you can't get the whole package on there, put the remainder back in the fridge for later. 

Do not preheat your oven. When you have as much bacon as you can fit on your sheet pan, place it in a cold oven and set the oven to 400°F (204°C). 

Set a timer for 20 minutes and start checking the bacon. Depending on the type of bacon and thickness, it could take another 5 or more minutes. 

I start checking at 20 minutes, and if it's not fully done, I will flip the bacon and put it back in the oven for another 5 minutes or so, checking the doneness every so often. Once the bacon is done to your liking, remove the slices to a paper towel-lined plate and store in the fridge if you're not using it immediately. 

Once you've removed the bacon, you can carefully pour off the bacon grease into a jar or heat-proof container before it cools and firms up. You can use the bacon grease in the bread toasting or egg cooking process if you want. 

Pre-sandwich assembly: to get the sandwich build started, we need to toast the bread slices and get the cheese melty. I accomplish this in a medium-sized non-stick pan that you would typically use to cook an egg. Place the pan over medium-low heat. Spread a bit of fat in the form of butter, mayonnaise, or bacon grease on the exterior of one side of both pieces of bread. Add the pieces to the pan, fat side down, and then add the slices of cheese to one slice of the bread. 

Place a lid over the pan to help the cheese melt. If you do not have a lid, you can use a sheet pan and lay it on top of the pan. We're just trying to trap some heat and steam in the pan to melt the cheese. Once the cheese is melted (should take 4 minutes or so) remove both slices of bread to a cooling rack while you build the sandwich and cook the egg. 

Spread mayonnaise on the slice of bread without cheese. Top the mayo with the slices of tomato and then season the tomato slices with a pinch of salt and pepper. 

Top the tomato slices with your bacon, making sure that the slices are spread out and cover the full amount of the bread. Lay the lettuce pieces on top of the bacon and get ready to cook your egg.

Fried egg: wipe out the pan from toasting the bread and add it back to medium or medium-low heat. Add a tablespoon of butter or bacon grease to the pan and allow it to warm up while you carefully crack an egg into a bowl, doing your best not to break the yolk. You crack it into a bowl first so that you can make sure there's no shell in the hot pan.

When the butter or fat is bubbling and hot, carefully pour the egg into the pan, again taking care that you do not break the yolk. Season the egg with a pinch of salt and ground black pepper. 

Cook the egg until the white part around the yolk is starting to solidify and isn't super runny. At this point, you can carefully flip the egg in the pan to make an over-easy egg, or you can just use a sunny-side-up egg in the sandwich. Basically, flip if you prefer your egg just a little more cooked, but be very careful not to break the yolk. 

Once the egg is cooked to your liking, remove it from the pan and carefully lay it on top of the lettuce. Carefully close the sandwich by placing the slice of bread with melted cheese on top of the egg. 

Slice the sandwich with a sharp knife over the part where the egg yolk should be and serve. Dip the sandwich in the spilled egg yolk for a bit of sauce on each bite.