Add the bacon to a large skillet over medium-high heat and cook for 4-5 minutes, flipping halfway through, until crispy. Transfer to a plate lined with paper towels and let cool slightly, then crumble or chop into pieces and set aside. Discard the bacon grease and wipe the skillet clean with a paper towel. If you like cooking with bacon grease, you can use it to cook the eggs instead of using the olive oil.

Heat 2 teaspoons of olive oil in the same skillet over medium-high heat. Add the onion, tomato, and jalapeño and cook for 5 minutes, stirring occasionally, until the vegetables are soft and tender.

While the vegetables are cooking, whisk together the eggs, salt, and black pepper in a large bowl. Pour the beaten eggs into the hot skillet and let sit for 10-15 seconds, then stir often until the eggs are just set and mixed with the vegetables, about 1-2 minutes. Transfer to a bowl and set aside.

Assemble and cook the quesadillas by sprinkling shredded cheese on one half of each tortilla. Top with a layer of the scrambled egg mixture, some crumbled bacon, and a final layer of shredded cheese.

Fold the tortillas over and cook in the large skillet with melted butter over medium-high heat for about 1-2 minutes per side, until the cheese starts to melt and the tortilla starts to get crispy.

Transfer the quesadillas to a cutting board and cut in half. Serve with your favorite salsa and sour cream.