Cook bacon in a large skillet over medium heat until extra crispy, about 8-10 minutes, flipping occasionally for even browning. Transfer cooked bacon to paper towels to drain excess grease, then crumble into bite-sized pieces once cooled slightly. Set aside.
Crack 6 eggs into a medium bowl and whisk vigorously with a fork or whisk until fully combined and slightly bubbly. Season generously with salt and freshly ground black pepper to enhance flavor.
Melt 1 tablespoon of butter in the same skillet over medium-low heat, swirling to coat the entire cooking surface. Pour whisked eggs into the buttered skillet and let them sit undisturbed for 30 seconds until edges begin to set.
Using a rubber spatula, gently push eggs from the edges toward the center, creating soft fluffy curds as they cook. Continue cooking and folding for 3-4 minutes until eggs are just set but still slightly glossy. Remove from heat immediately to prevent overcooking.
Lay one tortilla flat on a clean work surface. Sprinkle one-quarter (about 1/4 cup) of the shredded cheese over half of the tortilla, leaving the other half bare for folding.
Spoon one-quarter of the scrambled eggs onto the cheese-covered half of the tortilla, spreading them evenly. Top with one-quarter of the crumbled bacon pieces, distributing them across the eggs.
Fold the bare half of the tortilla over the filled half, pressing gently to help cheese and ingredients adhere together. The quesadilla should form a half-moon shape. Repeat assembly process with remaining three tortillas to create four folded quesadillas total.
Heat a clean non-stick skillet or griddle over medium heat. Add a small pat of butter (about 1/2 teaspoon) to lightly coat the cooking surface, or use cooking spray if preferred.
Place one folded quesadilla in the hot skillet and cook for 2-3 minutes until the bottom turns golden brown and cheese begins melting. Press gently with a spatula to ensure even contact with the hot surface.
Carefully flip the quesadilla using a wide spatula and cook the second side for another 2-3 minutes until crispy and golden brown. The cheese should be fully melted and oozing slightly from the edges.
Remove cooked quesadilla from skillet and let it rest on a cutting board for 1-2 minutes to allow the cheese to set slightly, making it easier to slice without spilling the filling.
Slice each quesadilla into thirds or quarters using a sharp knife or pizza cutter. Serve immediately while hot and crispy, garnished with sour cream, salsa, sliced avocado, fresh cilantro, or your favorite toppings.
