Using an electric mixer on medium speed, blend the cream cheese, egg, and ⅓ cup sugar for 2-3 minutes or until fluffy. Stir in butterscotch chips.
FOR THE BUTTERSCOTCH CUPCAKES
Preheat oven to 350 F and line 2 muffin tins with cupcake liners.
Whisk together the flour, salt, and baking soda and set aside.
In the bowl of an electric mixer or in a large bowl using a hand held mixer, mix together the oil, sugars, egg, and vanilla extract on medium speed until combined. Add the milk alternatively with the dry ingredients and mix until just combined.
ASSEMBLING THE CUPCAKES
Spoon the cupcake base into each muffin cup until about 1/3 to 1/2 full. Add a heaping tablespoonful of the cream cheese mixture on top. Continue to fill all the muffin tins.
Bake 14-16 minutes or until a toothpick, when inserted in the cupcake, comes out clean.*
Allow cupcakes to cool in pan 10 minutes and then transfer them to a rack to cool completely.
Notes
*When testing for doneness, try to stick the toothpick into the cupcake part not the cream cheese part. The cream cheese part should remain a bit gooey. If you stick the toothpick in the cupcake part, the toothpick should not come out gooey.