Once the broccolini has been washed and dried, trim ½ an inch off the bottom of the stems. (You can keep on the dark green leaves and yellow flowers - they're edible.) Set them next to the stove along with your minced garlic.
Heat a large skillet over medium heat. Once warm, add the butter, olive oil, and minced garlic. Stir frequently, so the garlic becomes aromatic but doesn't burn. After about 20 seconds, add the broccolini and the salt and pepper.
Saute for 3-4 minutes, turning the broccolini in the pan frequently. Then, pour in the broth immediately followed by a lid, and steam for 3 minutes. Arrange on a serving plate and sprinkle with nutritional yeast (optional). Serve with lemon wedges.