Liza, I’ve made this recipe as cupcakes a few times now.
I don’t adjust leavening and I allow the batter to sit in the cupcake pan for ~20 min before baking to achieve a domed top. If you want a flat top, just bake them right away.
They are sensitive to over baking/drying out; they’re often over baked by the time the top springs back slightly or the toothpick comes out clean. (my usual tests for doneness). I’m relying more and more on internal temperature. I didn’t make a note, but I think 196-200F works.
I often frost them, freeze them and then wrap each one well with plastic wrap. I think frosting them and baking them in paper liners helps to keep them moist.
I normally make 12 from 1 batch of batter and they bake for 20-21 min. I’ve included a photo of 1 to give you an idea of size (the awful magenta colour is courtesy of Club House brand food colouring ).