Start this recipe by half cooking the paccheri pasta in salted boiling water. Drain the pasta and put aside. Meanwhile, you can prepare the filling. Heat the olive oil in a pan and brown the bacon for 2 minutes. Add in the garlic and onion and sauté for 3 minutes to soften. Add in the thyme leaves and pumpkin and season well with salt and pepper. Allow to the pumpkin to cook for 5 minutes then remove off the heat. Use the back of a spoon the mash the cooked pumpkin, then stir in 1 tablespoon of Parmesan cheese along with the ricotta. Spread a tablespoon of the becamel sauce in the bottom of an ovenproof dish. Use a piping bag to fill the half cooked paccheri then place side by side in the oven dish. When they are all filled, top with the remaining béchamel sauce then scatter over the 2 tablespoons of Parmesan cheese. Bake in the oven at 200`c for 15 minutes, or until the top is golden brown and bubbling. To serve, place the paccheri onto your serving plates and top with fresh salad leaves to garnish.