You can try to set such button hole with the help of a sewing machine, but they aren't always smooth and not always have a beautiful view. I propose to Refine them.

1. Apply a piece of water-soluble film on top and water-soluble fusible webbing from the inside. Stitch on the machine:

2. Remove the remains of the fusible webbing and file with a damp sponge:

3 . Cut the hole through.

4. Needle a thread half the thickness of the yarn and sew along the perimeter.

Get a plump hole :)