I got a small cream pitcher, probably at WalMart or some such place, years ago. It's about 1/2 cup, just like this!! (too funny), and I use it in the microwave all the time to heat up milk. I have a larger stainless pitcher for frothing.

Amazon has a good selection.

I would just put the amount of milk you want to heat up in a 1-cup glass measuring cup.

I just put the milk in my coffee mug, microwave that, then pour the coffee into that mug. Repeat as needed. However, if you specifically want a 4 oz. creamer/pitcher, here's a MW-safe one. There's also the classic Apilco cow-shaped creamer. I also think this milk bottle creamer is cute, but it's larger than you want.

Thank you all for your ideas! I should be able to find something among them that will work. I so much appreciate you taking the time to give me ideas!!
Ginny