Heat a pan to medium and cook the bacon, turning halfway through, until crisp but not burnt. Remove bacon from pan, as well as bacon fat. Once cool, coarsely chop the bacon, or quickly pulse in a food processor.
Boil liberally salted water, add the gemelli, and cook 11 minutes or until al dente.
Lower the heat slightly, and add the olive oil. Once the oil is heated, add the diced onion and cook until just translucent, 5-8 minutes. Add the garlic and crushed red pepper and cook another 2-3 minutes.
Add tomatoes to the pan and turn the heat back up to medium.
Cook 10-15 minutes until sauce has thickened, stirring occasionally. Add cream and bacon and simmer until heated through.
Add pasta to the pan and toss to coat. If desired, add grated parmesan to serve.