Start this recipe by cutting the ends off the abergine and slice into 8 slices. Heat a griddle pan with olive oil and cook the aubergine slices on both sides. Remove from the pan and allow to cool. Meanwhile, mix together the ricotta, grated Parmesan, walnuts, thyme, lemon zest, tomatoes and spring onions and season well with salt and pepper. To put together, lay the aubergine slices out and cover each with a slice of speck. Spoon the ricotta filling equally onto each and lay over some rocket leaves. Roll up the aubergine slices to create nice involtini. Serve the involtini on a long board and spoon over some chopped fresh tomatoes. Toss over some extra rocket and Parmesan shavings, drizzle with oil and serve.