To assemble || Line up empty jars on the kitchen counter. Scoop about 1/3 cup pasta sauce into the bottom of each jar. Add the cheese in an even layer. Fill to about 1/4 inch from the top of the jar with the prepared pasta. Add a few more pieces of cheese and season with salt, pepper, and red pepper flakes. Seal the jars and store in the fridge for up to 4 days.
To reheat || Pour the contents of the jars into a microwavable bowl, give it a big stir, and microwave in 15-20 second intervals, stirring in between each cook time, until warmed through.