Cook pasta in a large pot of salted boiling water as directed on package. Cooke al dente and drain when done. Set aside.
Heat olive oil in a large pan over medium high heat. Cook ground beef and onion until beef is browned and no longer pink and onion is soft.
Drain excess fat if desired. Set beef aside.
Place the skillet back on the heat and add garlic and seasonings to the pan and cook for 1 minute or until fragrant.
Whisk in the flour and stir to cook our raw flour taste.
Whisk in beef broth and stir to mix.
Pour in marinara sauce.
Bring to a boil and reduce heat to a simmer. Stir occasionally for 5-7 minutes or until the sauce thickens slightly.
Stir in the pasta and beef/onion mixture.
Add the sour cream and stir to combine and make the sauce creamy.
Fold in mozzarella cheese and stir until melted.
Remove from heat and serve warm.
Garnish with fresh chopped parsley.
Notes
For a creamier sauce, reserve 1/2 cup of the pasta water to add. Replace part of the broth with it.
Eliminate the large skillet and make this a one pot meal. Use a dutch oven or large pot to cook your shells AND cook the rest of the meal. Easy clean-up!
There are many different ingredients you can use to garnish this dish. Fresh basil, red pepper flakes, chopped thyme or parmesan cheese.
This hearty pasta dinner is fine all by itself, but you can serve it with garlic bread or a green salad for a complete meal.
Leftover beef and shells will last in an airtight container in the fridge for up to 3 days.
This is a great recipe for a freezer meal. Prepare the recipe and allow it to cool to room temperature. Place in an airtight container or freezer bag and store for up to 3 months. Simply thaw, reheat and serve.