1Heat oven to 350°F. Grease bottom and sides of 8-inch square pan with shortening or spray with cooking spray; lightly flour.
2In medium bowl, beat all ingredients except chocolate syrup, 1/2 teaspoon cinnamon and the ice cream with electric mixer on low speed 30 seconds, scraping bowl frequently. Beat on medium speed 4 minutes, scraping bowl occasionally. Pour into pan.
3Bake 30 to 35 minutes or until toothpick inserted in center comes out clean.
4Meanwhile, in 1-quart saucepan, heat chocolate syrup and 1/2 teaspoon cinnamon over medium-low heat, stirring occasionally, until warm. Serve sauce warm or cool. Drizzle sauce over warm or cool cake. Serve with ice cream.