Take the artichokes and cut off the stems, plus ¼-½ an inch of the bottom off. You want to have the bottom fairly flat. Also remove the first bottom layer of the leaves. These tend to be tough. You may find you do not need to remove the bottom leaves becasue they fell off when you were cutting the stem off.
Cut off the top off, about an inch, to expose the inside. Also the leaves tips are sharp, so I like to take kitchen scissors and trim the tips too.
Place the artichokes, tops down, in the Instapot with one of the lemons that has been sliced thinly. Take the other lemon and squeeze the juice over the artichokes. Pour in the chicken stock and cook on high for 15 minutes.
When the Instapot finishes, rapid release the steam and take the artichokes out. Place in a baking dish, stem side down. Take a spoon and dig out the center part of each artichoke. You don't want to eat this part anyway,
Once the inside part of the artichoke has been removed, take the butter, garlic powder, salt, and pepper and melt it all together in a microwaveable bowl. Pour over the tops of the artichokes.
Sprinkle the parmesan cheese over the tops of the artichokes and place in a preheated 375°F oven for 5 minutes to melt the cheese. Serve immediately.