Combine breadcrumbs, nuts, chilli flakes and 1 teaspoon salt in a bowl. In another bowl, flake the tuna into large chunks.
Cook pasta in a saucepan of boiling salted water until al dente. Drain pasta then transfer to a large bowl.
Return pan to stovetop over low heat. Add oil and garlic and spinach, and cook until fragrant. Add crumb mixture. Cook, stirring until golden. Add to hot pasta with parmesan, tuna, and mayo, lemon rind. Toss well to combine. Season to taste. Toss gently. serve.