Bring a large pot of lightly salted water to a boil. Add penne and cook, stirring occasionally, until tender yet firm to the bite, about 11 minutes. Drain and set aside.
Heat oil in a large skillet over medium heat. Remove casing from sausage and add to the skillet. Cook and stir until crumbly and brown, 5 to 7 minutes. Add garlic and red pepper flakes; cook and stir until garlic is golden brown.
Add tomatoes and salt; bring to boil. Reduce heat and simmer for 15 minutes.
Add cream and vodka; bring to boil. Reduce heat to low and add pasta; toss for 1 minute. Stir in parsley; serve warm.