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.
Cupcake Batter
Preheat oven to 350 F and line 2 muffin pans with paper liners.
In a medium sized mixing bowl, 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.
Assembly
Spoon the cupcake batter into each muffin cup (one tablespoon at a time being careful not to overfill) until about 1/3 to 1/2 full. Be careful not to fill them more than that. Add a heaping tablespoonful of the cream cheese mixture on top.
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
Filling cupcakes: Be careful not to overfill cupcake pan. Fill cupcake liners only 1/3 to 1/2 full with batter. For this recipe, I recommend adding the cupcake batter one tablespoon at a time. This will make it easier to avoid adding too much batter. Doneness: Stick a 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.Cream cheese: Room temperature brick style full fat cream cheese. Do not use the kind of cream cheese found in a tub.
Storage: Store cupcakes in an airtight container in the refrigerator for up to 5 days. Serve at room temperature.