Creating a darker image isn’t about underexposing your image, it’s about guiding the light to do what you want it to do.
In this image, I created a really simple set up and started with 2 surfaces, using our Dexter surface for the table top, and Ash for the background wall.

Since most folks working from home are using natural light, I decided to do the same here. In this shot, the light source is coming from the right. I have a wall of South-facing windows in my studio so, during the middle of the day when this was taken, the light is abundant. My goal here was to have light hitting the side of the bundt cake, showing the shape and texture, but have the rest of the image fade into darkness. To achieve this, I hung a black board on the right side of the set in order to block the light from most of the shot.

I set my aperture at F4.5 to have enough of the cake in focus where it wouldn’t be visually confusing but would also provide a fairly shallow depth of field, allowing the background to become soft as it became darker. My corresponding shutter speed was at 1/30 so I had my camera on a tripod, avoiding any camera shake that could occur if it was handheld.

In addition to blocking much of the light on the right side, I avoided using any kind of bounce or reflector on the left side, as I wanted to dark side of the subject to have rich shadows, (note: If I had wanted to make my shadows extra dramatic, I could have added a second black board on the left but I didn’t do that here.)

Also, I picked props that were all in the same color family as my surfaces: mostly cool toned, darker items in the blue-gray range. Because the cake is warm toned, it stands out even more against the contrasting colors.

And that’s it! Super simple and easy to do at home. :)