Fill a large pot with water, adding a pinch of salt, and bring it to a rolling boil over high heat. Once boiling, add the cheese tortellini and cook according to package instructions, typically 3-5 minutes, until they float and are tender yet firm. Drain and reserve a bit of pasta water.

While the tortellini cooks, rinse and slice the cremini mushrooms and chop the fresh sage leaves. Heat a large skillet over medium-high heat and add a tablespoon of olive oil. Once the oil shimmers, toss in the chopped sage and fry for about 1 minute until crispy. Remove the sage with a slotted spoon and set aside on paper towels.

In the same skillet, add another tablespoon of olive oil and a tablespoon of butter. Once the butter melts and bubbles, add the sliced mushrooms and sauté for about 5 minutes, stirring frequently, until golden brown and tender. Add minced garlic in the last minute of cooking.

Reduce heat to medium-low and add the drained cheese tortellini to the skillet. Toss gently to combine, then add another tablespoon of butter, allowing it to melt and coat the pasta evenly.

Sprinkle in the crispy sage along with freshly grated Parmesan cheese, and toss until well combined. Taste and season with salt and pepper. Serve immediately, garnished with extra cheese if desired.