The short answer is that you can just stack them. For instance:
This machine will make doughnuts simply and quickly.
The longer answer is that you can have multiple adverbs in a sentence, but just like in English, where you put them changes what it applies to. Quantifier adverbs (とても, ちょっと, あまり etc.) are great to demonstrate this. For instance:
The girl read the very interesting book leisurely.
The girl read the interesting book very leisurely.
If you are using, say, three adverbs applying to a verb, it might be a bit much (as it would be in English), but it's fine not to do anything special. It might be helpful to add some 、 to help the reader/pauses to help the listener, but again, it is not necessary.
This machine will make doughnuts simply, quickly, and efficiently.
However, you might be better off thinking about if there's emphasis to add in this sort of sentence, by using something like しかも (moreover) to punctuate the phrase. Again, this might make the sentence easier to parse for the reader/listener.
This machine will make doughnuts simply, quickly, and moreover efficiently.
Hopefully that helps!