Hi - can this batter be made 2 days ahead and kept refrigerated? Thanks!

I would avoid mixing the batter 2 days ahead. The reason is that when the leavening agent meets the wet ingredients it will start to work to leaven the batter (the application of heat in cooking completes the job). What you could do, and what I often do for other batters (like cakes) is mix all the dry ingredients (the first 5) per the recipe and store them in a zipper lock bag (or in a small bowl, covered). Mix the wet ingredients according to the recipe in their own separate container (blitz in the blender, holding back some of the milk as the recipe states); refrigerate. I'd probably keep the seasonings separately, measured out and ready to go, except the scallions and cilantro, which I'd wash, dry and trim ahead of time but would slice just prior to cooking. When you're ready, combine ingredients and cook.