Place cream cheese in a cast iron skillet or smoker safe dish. Use the tip of a sharp knife to cut/score crosswise slices in the cream cheese, about ½ inch deep.
Brush the cream cheese with oil and beer. Pour the remainder of the beer in the skillet.
Cover the cream cheese with sweet BBQ rub and use your fingers to pat it gently, to help it adhere.
Surround the cream cheese with sliced onions and jalapenos if desired.
Smoke for 1 hour, tossing the onions and jalapenos often to ensure coated with liquid and prevent from drying.