Combine olive oil, garlic salt, and black pepper in a bowl.
Trim the ends off of each sprout then slice them in half lengthwise.
Toss the trimmed sprouts with the olive oil mixture until well coated.
Place sprouts, cut side down, onto a baking sheet.
Roast in oven for 35-40 minutes, or until tender when pierced with a fork.
Notes
Choose Brussels sprouts that are bright green in color with tightly wrapped leaves.
We like to use garlic salt, but regular salt works just as well. On top of the salt you just need black pepper and olive oil. This creates a good base for any other additions after cooking such as parmesan cheese, cooked bacon, crumbled feta, etc.
If you plan on making a big batch for a holiday gathering, you can trim and slice the sprouts a day ahead of time and store them in an air-tight container in the refrigerator. Toss with olive oil, salt, and pepper right before roasting.
Store cooled leftovers in an air-tight container kept in the refrigerator for 3-4 days. Reheat in a 350F oven on a baking sheet until warmed through. You can also place them in an air fryer and use the reheat function to warm them back up. You can reheat them in the microwave, but using an oven or air fryer is your best bet for crispiness.