You'll need to post a couple of pictures of the area. We don't know what the brick and backsplash look like and where this is so it would be difficult to help.

How would some moulding look. I caulked a dowel into place and painted it.

If you already did that, can you show a pic? More importantly, do you think it looks okay?

I will post a picture if I can find the attachments for my camera, which I can't at the moment. I did this in a basement apartment where I installed second hand cabinets (nice white ones) and counter. Because I put beadboard on the backsplash (to help cover the gap), I figured a dowel would match nicely. It actually looks really nice, like it was done for no reason. I painted the beadboard and dowel white. You could look at mouldings, take one home and try it out. You could glue it in place with PL (construction adhesive) if you are attaching to brick and paint it to match.

Because I don't know what your counters look like, it is harder to advise. If your counters are solid color laminate, you could match the color and it would look pretty good.

If you have a higher end kitchen with granite, etc. you could either (a) if you have no backsplash, have a carpenter scribe (with a compass along the wall and the countertop) so that you have an exact replica of the ins and outs of the wall) and then remove the countertop and shave the edge with a plane to match. Of course, you could remove the caulking with a heat gun first. This option works best if you don't have the sink in the same counter.

(b) if you have a backsplash, you could have a moulding made of the same material as your countertop and glued in place on the top of it. I would set it back l/8 of an inch. That is a more expensive option.

If the reason the contractor made such a large gap was because of the brick going in and out, scribing is the way to go. If he didn't push the counter in far enough, you could of course remove the screws, push it into place and drill and reattach the screws.

I have since looked up granite countertops and apparently they are hard to move because they could break at a seam or whatever. I would talk to a professional before doing that. If you don't have a backsplash, you could add one to match the countertop or add tile behind it.