Place the cubed bread in a bowl and toss with the olive oil, Parmesan and a pinch of salt and pepper. Transfer to a sheet pan and bake until golden and crisp, 12 to 14 minutes.
Meanwhile, chop 4 chipotle peppers into a paste and mix with the Caesar dressing in a bowl. Stir until well combined, then set aside.
Preheat a grill pan over medium heat.
Brush the salmon lightly with olive oil and sprinkle with a pinch of salt and pepper. Pour a little oil over the grill pan and add the salmon. Cook until nice grill marks have formed, 3 to 4 minutes. Brush the tops of the salmon fillets with more olive oil and flip over. Chop the remaining chipotle pepper and combine it with the adobo sauce and a couple of tablespoons of olive oil. Brush the mixture over the salmon as it grills. Continue to grill the salmon until cooked through, an additional 8 to 10 minutes, depending on the thickness. Set aside to rest.
Combine the lettuces in a large bowl, then season with a pinch of salt and pepper and toss with the dressing until well coated. Add the toasted ciabatta and toss. Transfer to a large platter and top with the grilled salmon fillets. Halve the lemon and cut one half into wedges to garnish the platter. Squeeze over the juice of the other half, then serve.