Step 1: Preheat oven to 400°F (200°C). Season chicken breasts generously on both sides with salt and pepper.
Step 2: Set up dredging stations: In one shallow bowl, combine all-purpose flour with 1 teaspoon of garlic powder. In a second shallow bowl, add panko breadcrumbs. In a third shallow bowl, whisk 1-2 large eggs for an optional egg wash.
Step 3: Coat each seasoned chicken breast first in the seasoned flour (shaking off excess). If using, dip into the egg wash, letting excess drip off. Finally, roll generously in the panko breadcrumbs, pressing gently to ensure they stick well.
Step 4: Arrange coated chicken breasts on a baking sheet (lined with parchment paper for easy cleanup, or lightly greased). Bake for 25-30 minutes, or until golden brown and cooked through to an internal temperature of 165°F (74°C).
Step 5: While chicken bakes, prepare the garlic mayo: In a medium bowl, combine mayonnaise, minced fresh garlic, the remaining 1 teaspoon of garlic powder, and lemon juice. Stir until smooth and creamy. Taste and add more salt and pepper if needed.
Step 6: Once chicken is done, remove from oven and let rest for 2-3 minutes to keep it juicy. Assemble sandwiches by placing a crispy chicken breast on the bottom half of a soft bun. Spread garlic mayo generously on the top bun. Add any desired extra toppings like lettuce, tomato, or pickles. Serve immediately.