The only thing Shelda eats in Bugsnax is cheese sauce, apparently, and she wants you to bring her some. This is actually very easy to do, if you know where to look.
To the left of Shelda is a large stone monument with an open mouth. Inside the mouth grows two cheese plants. Take out your scanner and look for them, as it is the easiest way to spot them.
When you find them, you can use your Snak Grappler to pull them down. The Snak Grappler will clear the entire cheese plant of cheese sauce, pulling down five at a time. Hit them both, then return to Shelda and give her the cheese sauce that she desires.
That’s all you need to do for this step in Shelda’s quests, but it can be a little confusing as you will be used to looking for sauces on the ground. The entire Sizzling Sands area is like this, throwing curveballs when it comes to catching different types of Bugsnax in new ways, so keep that in mind as you play through it.
One of the more interesting Bugsnax you will find here is the Mothza Supreme, but you won’t have any way to catch it until you play all the way through Cromdo’s story, so don’t get too distracted by the giant pizza flying around the area.