Make the pesto by combining basil, garlic, parmsean, olive oil, and walnuts in a food processor or bender. Blend until fairly smooth.
Cut the focaccia loves in half carefully. Spread the pesto on the top halves and set aside.
On the bottom halves layer sliced chicken breast, and salami.
Mix sun-dried tomatoes, olives, pepperoncinis, and roasted red bell peppers in a small bowl. Sprinkle over meat layer.
Top with slices of fresh mozzarella to cover the entire sandwich.
Place pesto covered top half of the focaccia onto the sandwich. Wrap tightly in plastic wrap.
Place the wrapped sandwiches onto a baking sheet. Place another baking sheet on top of the sandwiches. Place 2 heavy books or weights on the top baking sheet to squish the sandwiches. Place in the fridge, books and all, for 12 hours.
Once 12 hours have passed, unwrap the sandwiches and slice into square for serving. Wrap in wax paper and cooking twine for a cutesy presentation.