Penne with shrimp, vodka & cherry tomatoes

½ pack of leftover cooked penne 400 g shrimp 2 tbsp olive oil 1 small onion, finely chopped 2 garlic cloves, minced 150 g cherry tomatoes, halved 50 ml vodka 200 ml heavy cream 1 tsp dried thyme Fresh parsley 50 g grated Parmesan Salt Pepper