Preheat oven to 400 degrees and line a baking sheet with parchment paper, foil or silicone liner.
In a small bowl, combine oil, lemon juice, cheese, oregano, salt and pepper and stir to combine. The mixture will resemble a paste.
Place artichoke halves (chokes removed) on the baking sheet with cut side up and evenly distribute the parmesan cheese mixture onto the halves. Make sure you thoroughly cover the artichokes and even try and get some of the mixtures in between the leaves.
Roast artichokes in the oven for 10 minutes to brown. Cover artichokes loosely with a piece of foil and continue to roast for 30-40 minutes until tender.