Honestly your best bet is buying samples of all butterscotch’s on the market (cap/TFA/FA I’m sure there is more) then mixing 5% in a 15ml bottle at your desired vg/pg and nicotine. Then just vape them and see what works. Even go mad scientist and mix match butterscotch to get your desired flavor. DIY or DIE did a video on butterscotch, it was very informative. I will try and post a link
IMO use 10 mil bottle, and look at the suggested single flavor amount on my favorite site ( :: Flavor list e-Liquid Calculator ) as the flavor may need 10%. 10 mil makes it so each 1% = .1 mil so easier math. and its cheaper to pour out 9.5 mils. And vape it side by side with your favorite looking for subtle differences and trying to identify those flavors. There is no hint in the reviews about a background flavor but the name “-YO” might be a hint that there is a wee bit of yogurt?