General Recipe Trouble Shooting

Hello, all. The other day I prepared a butterscotch pudding and topped it with unsweetened whip cream. By themselves both were...all right, but when eaten together I noticed a fatty residue on the roof of my mouth much like when an ice cream custard breaks during freezing. I've included the pudding recipe below as a reference. The only points where I deviated were the cassonade (which I didn't have on hand so used a mixture of medium brown sugar and molasses) and the vanilla extract (where I live the preserved vanilla pods in glass tubes are much easier to come by).