Chocolate Chip Cheesecake Swirl Cupcakes

1/2 cup sugar
2 packages (3 oz each) cream cheese, softened
1 egg
1 bag (6 oz) semisweet chocolate chips (1 cup)
2 1/4 cups Gold Medal® all-purpose flour
1 2/3 cups sugar
1/4 cup baking cocoa
1 1/4 cups water
1/2 cup vegetable oil
2 tablespoons white vinegar
2 teaspoons baking soda
2 teaspoons vanilla
1 teaspoon salt

1. Heat oven to 350°F. Line 24 regular-size muffin cups with paper baking cups. In medium bowl, beat 1/2 cup sugar and the cream cheese with electric mixer on medium speed until smooth. Beat in egg. Stir in chocolate chips; set aside.
2. In large bowl, beat remaining ingredients on low speed 30 seconds, scraping bowl occasionally. Beat on high speed 3 minutes, scraping bowl occasionally. Reserve 1 1/2 cups batter.
3. Fill each muffin cup one-third full (1 rounded tablespoon) with batter. Spoon 1 tablespoon cream cheese mixture onto batter in each cup. Top each with reserved batter (1/2 rounded tablespoon).
4. Bake 30 to 35 minutes or until toothpick inserted in center comes out clean.
High Altitude (3500-6500 ft): In step 1, decrease sugar to 1/3 cup; add 1 tablespoon flour to cream cheese mixture. In step 2, increase flour to 2 1/2 cups, decrease sugar to 1 1/3 cups and decrease oil to 1/3 cup. Reserve 1 1/4 cups batter.