Bring a large pot of salted water to a boil and cook the pasta shells according to package instructions until al dente. Drain and set aside.
While pasta cooks, cook the bacon in a large skillet over medium heat until crispy. Remove bacon and drain on paper towels, leaving the bacon fat in the pan.
Add diced onion to the skillet with bacon fat (or olive oil if preferred) and sauté until translucent, about 4–5 minutes.
Add the frozen chopped broccoli directly to the skillet and cook until heated through and tender, about 6–8 minutes, stirring occasionally.
Pour in the jar of tomato pasta sauce and stir to combine. Let it simmer gently for 5 minutes to meld the flavors.
Stir in the half-and-half to create a creamy sauce. Season with salt and pepper to taste.
Crumble the cooked bacon and add it back to the sauce, stirring to combine.
Toss the cooked pasta shells into the sauce until evenly coated and heated through.
Serve warm, optionally garnished with grated Parmesan or red pepper flakes for a bit of heat.