Looking to be able to run my counter top toaster oven and my counter top microwave off the same breaker without tripping. I need to save my counter space by stacking the units and sharing the outlet.
The problem is, you have both appliances on the same circuit.
Most kitchens are wired with two kitchen receptacle circuits for this very reason.
Running two high-power (heat making) kitchen appliances at the same time on the same circuit is simply a non-starter. Almost every heat appliance is 1500 watts, because that is the maximum UL will certify on a standard socket. The largest possible circuit for these appliances is 2400 watts, so 3000 watts is simply too much. Not gonna happen.
Honestly, you should know this (at least by now), and you should not be even trying. Intentionally creating an overload is asking for a house fire. Certainly when you do trip a breaker for a reason that you know to be overload, you should wait 15 minutes for the wires in the walls to cool down.
If you really, really need to have those appliances there, you can try a heavy extension cord (remember these are HEAVY appliances), but draping extension cords across potentially wet kitchen counters is a disaster of another kind - though much is forgiven if the outlets are GFCI protected (they either have obvious GFCI receptacles, or "GFCI Protected" stickers on them).
The better plan is to contact an electrician about bringing the other kitchen receptacle circuit to a new outlet here, or splitting the existing outlet.
Use a heavy duty extension cord for one appliance to another circuit. N.B. Normally, this is inadvisable due to heating of the cord and voltage drop, but if you get one with sufficient current rating, it should be OK during the time the appliance is in use *if you are in the kitchen, paying attention.
Check the current rating of the device and get an extension with a bit of margin above that.
Never use an extension for a unattended, high-current, device.