Step 1

Heat butter or olive oil in a large saucepan (or deep sauté pan) over medium-high heat until melted.  Add crushed red pepper flakes and sauté for 2 minutes, stirring occasionally.  Add onions and sauté for 5 minutes or until softened and translucent, stirring occasionally.  Add garlic and sauté for 2 more minutes or until fragrant, stirring occasionally.  Add in the tomatoes and stir to combine.

Step 2

Continue cooking the sauce, breaking up the tomatoes with a wooden spoon (or potato masher) as you go, until the sauce reaches a low simmer.  Reduce heat to medium to maintain a steady simmer.  Then let the sauce continue to cook uncovered for about 25-30 minutes, stirring occasionally, until it has thickened** and reached your desired consistency.

Step 3

Stir in the basil, salt and pepper.  Then taste the sauce, and season with any extra salt, pepper and/or crushed red pepper flakes as needed.

Step 4

Serve immediately.  Or let the sauce cool and then refrigerate it in a sealed container for up to 4 days.