Yup...ask the provider. As a provider, I prefer parents to bring the mini cupcakes, or the frosted cookies or something else. Big cupcakes are just too big, messy and they just lick the frosting off.
I had one parent (her daughter was in my care from the age of 18 mos to 9 years old). She would bring breakfast every year! Always with approval from me. Usually we would actually eat it as our lunch that day. Quick pancake mix, the stuff for french toast, instant cook sausage, OJ, etc. Always was easy/instant cook stuff really, I just didn't have everyone arriving at the same time in the mornings, so it was hard to make it our first meal of the day. But it became their tradition and we looked forward to it every year. One year it was fancy huge muffins from the coffee shop (and coffee for me!). It was fun! (The little girl still to this day..we keep in touch via FB....hates cake. She does pie or fancy cookies, ice cream cakes, etc for her birthdays).
Always check with your provider first!
Happy birthday to your little fella!