It'll work fine for what you need then. The IC3500 has a 3-wire , 3 pole outlet as well. So you'd just need to get 2 work boxes, a new pig-tail that matches the one on your stove, a section of wire rated for 240v (#12 gauge at least since the IC3500 will pull 3500w), another wall plug that matches your stove (NEMA 10-30 most likely from what you've said) and one for the IC3500 (I forgot what it needed).
So you'd build basically then wire the new pigtail into the work box to the new NEMA 10-30 outlet. Then cut a section of the #12 gauge wire, wire it to the 10-30 outlet as well, run it out of the workbox to the next workbox. In that box, put the outlet for the IC3500 and wire it in.
Then you'd plug this cable into the wall in place of the stove, plug the stove into the first box, then plug the IC3500 into the 2nd work box. No big deal since both appliances are 3 prong connections rather than 4.
I'd advise against running both at the same time. But one at a time should be no problem.
A crude drawing of this is attached in case the above description is unclear.
You could skip the new plug for the stove and go straight out to a workbox for the outlet for the IC3500 if you wanted, you'd have to unplug the stove anytime you wanted to brew then, but it would work just as well.
Yeah, that would work. the 20A breaker in between is not "really" needed.
But I would use the appropriate NEMA 6-20 receptacle to plug your IC3500 plate in directly instead of the second 10-30, which would need again an adapter.