If you are using raw shrimp, make sure the shrimp are shelled, cleaned, and deveined. Butterfly them for a nice presentation. If you are using already cooked shrimp, just remove the tails and check for any sand vein.

Start a large pot of salted water to boil for the pasta. Put the pasta in and cook until it is al dente. Drain and set aside.

Melt the butter in a large saute pan. Add the garlic and saute until it turns translucent. Don't let it burn!

Add mushrooms and saute them until they have slightly browned. Add the sun-dried tomatoes and saute them a bit, too.

Finally, add the shrimp and saute them until they are pink. If you are using already cooked shrimp, just saute until they are warmed through, don't overcook. Squeeze a half lemon over and mix together.

Add the cooked pasta to the pan, and top with the pesto sauce.

Combine all together, put in a large pasta dish and serve with the lemon slices.