Encasing one object in another

I am new here so not sure if this is the right place. I wanted to create a wood slab inside a glass. I have tried a couple of ways, just not sure how to approach it. First I just left the default cube than tried to create a grid than tried to separate the middle piece. Kind of like a video I saw on modern architecture where they created the shell of the house then created a grid and separated for the windows. I got lost. So, any suggestions would be greatly appreciated.

You could make two cubes and then scale one down