Bring a large pot of salted water to boil. Drop tortellini in water and cook for 7-10 minutes till done. While pasta is cooking, melt butter in large saucepan over medium heat. Add shallots and cook till lightly browned. Add garlic and red pepper flakes. Cook about 1 minute till fragrant. Add tomatoes and vodka. Simmer about 7 minutes stirring occasionally till alcohol cooks off. Season with salt and pepper. Add in heavy cream, stirring to combine. Cook another 2 minutes to heat cream. Add cooked pasta to sauce. Transfer to platter and serve with grated parmesan cheese.