Background Pony #F9E8
It looks like this started from a scene in No Second Prances, got changed to Twilight Sparkle 2.0 and a base and posted to an Instagram account “thtwilightsparkle” for the purposes of making collabs - no idea if they made the base or the picture of Twi or if they just edited in someone else’s - and of course no idea who made this resultant pic with Pumpkin Cake. So, no idea how to tag for credit.