depth of field - How to focus on an area correctly, while still blurring everything else?

I made a picture (see below) of an almond cake with the following settings:

• 4/3 sensor


• 25mm focal length


• Aperture f1.4


• Shutter speed 1/30 sec

I chose an appropriate shutter speed with the biggest aperture possible because I wanted to focus on the almond cake, blurring anything else.

If you look closer then you can see that the front part and the upper left part of the cake are kind of blurred also.

How can I avoid that? I'd like to have the cake focused as much as possible.