Heat the olive oil in a large saucepan over medium heat.
Add the chopped onion and cook for 5 minutes, stirring occasionally, until softened.
Add the minced garlic and cook for 1 minute until fragrant.
Add the halved cherry tomatoes to the saucepan and stir to combine.
Add salt, black pepper, dried oregano, dried basil, red pepper flakes, and tomato paste. Stir well.
Bring the mixture to a simmer, then reduce heat to low and cook uncovered for 25 minutes, stirring occasionally, until the tomatoes break down and the sauce thickens.
Remove the sauce from heat and stir in the chopped fresh basil leaves.
Allow the sauce to cool completely before portioning into freezer-safe containers or bags.
Label and freeze the sauce for up to 3 months.
To use, thaw the sauce overnight in the refrigerator and reheat on the stove before serving with your favorite pasta.