Step 1

Heat 1 tablespoon olive oil on medium-high heat in a large skillet. Add sliced onions and cook on high heat for about 10 minutes, constantly stirring with the spatula.

Step 2

The onions should start to brown, but without burning.

Step 3

Reduce heat to medium and continue cooking onions for 10 more minutes, continuing to stir, as onions brown even more without burning. At this point add a pinch of salt over onions.

Step 4

Continue cooking for 10 more minutes on medium or low heat, stirring occasionally to make sure onions don’t stick to the bottom of the pan or burn.

Step 5

In total, you should have cooked onions for 30 minutes.

Step 6

Remove the skillet from heat and sprinkle the onions with a small amount of balsamic vinegar to deglaze the pan.

Step 7

Using a spatula, stir the onions, scraping the bottom of the pan and coating onions with a pinch of balsamic vinegar you just added. Remove caramelized onions to a plate.

Step 8

Heat 1 tablespoon olive oil in the same skillet on medium heat. Add sliced mushrooms. Sprinkle with a pinch of salt.

Step 9

Cook mushrooms for about 5 minutes, occasionally stirring, until mushrooms are soft.

Step 10

Add fresh spinach to the skillet and stir on low heat just until spinach starts to wilt.

Step 11

Add half-and-half to the mushroom and spinach mixture and bring to a quick boil. Immediately reduce to simmer.

Step 12

Add 2/3 cup of shredded Parmesan cheese and 1/4 teaspoon salt. Keep stirring while the sauce simmers until the cheese melts.

Step 13

Add caramelized onions back to the skillet with the pasta sauce.

Step 14

Cook pasta according to package instructions. Drain.

Step 15

Add cooked and drained farfalle pasta to the creamy sauce. Stir on low heat for a couple of minutes to reheat.

Step 16

If the sauce is too thick, add a small amount of half-and-half to thin it out. If it is too thin, add a small amount of shredded Parmesan cheese, and stir it in, while the sauce simmers.

Step 17

Serve with more shredded parmesan cheese sprinkled on top.