I'm in PA and just starting to navigate the system. It is fairly easy (from what I have done so far) to bake "non-potentially hazardous" cakes from a home kitchen. In other words, nothing that needs to be refrigerated.
In general, first you would contact your township/borough and get the zoning office to give you permission. This has been my one tricky part as I got permission to "work from home" but not to "open a business" in a residential area based on the phone call I had. I now need to go back and get a letter stating this for my next step. (Hoping they will give that to me...fingers crossed).
Next you fill out the application that you can get online and send it in to the department of agriculture.
Once the PDA contacts you they will come do a kitchen inspection. If you pass you give them $35 and you are good to go.
I also just got my DBA and registered with the state for my sales tax license. Both very easy, but I had legalzoom take care of the DBA just for the ease.
What part of PA are you thinking of moving to? This is info that I have discovered from Allegheny County. Not sure if other areas are different.