In a small bowl, whisk together sauce ingredients until blended.
Bring a large pot of salted water to a boil.
Add the pasta, stir, and cook pasta according to package instructions.
Drain and set aside.
While pasta is cooking heat 3 teaspoons of olive oil in a heavy skillet.
Add the diced garlic and saute about 1 minute. Don't let it scorch.
Stir in the tomatoes, onion, and pasta.
Continue to cook over medium heat, scraping the bottom of the pan often, for about 3 - 5 minutes, or until the penne pasta starts to caramelize and get a golden crust.
Stir in the balsamic mixture and the spinach.
Saute just until the spinach wilts.
Garnish with shaved Parmesan and serve.
Storage:Cool to room temperature and cover leftovers with plastic wrap or place in an airtight container and refrigerate up to 3 days.Tips:
Pasta should be cooked al dente - it should taste a little firm, but still tender enough to be chewable.
As with most pasta dishes, never rinse your noodles after straining them (this rule doesn't apply for chilled pasta recipes, FYI.) The starchy residue left in the water on the pasta helps warm sauce stick to the noodles better.
Make sure your water is salted well and has come to a rolling boil before adding your pasta—it really makes a difference in the end result!
Using fresh basil is key for optimal flavor! The leaves should be bright green and not show any signs of discoloration or wilting.
To easily peel fresh garlic cloves, smash them under the thick end of your knife using the base of your palm. The peel will split and you should be able to squeeze the garlic right out with minimal effort.