1. Heat oven to 350 degree F. Grease and lightly flour two 9-inch round cake pans. Set aside.
2. Combine flour, baking soda, and salt in a bowl. Beat butter and sugars in another bowl until fluffy, 2 minutes; beating in eggs, one at a time.
3. Microwave chocolate chips on high 1 minute; stir until melted. At low speed, beat chocolate into butter mixture. Gradually beat in flour mixture alternating with the buttermilk and vanilla extract, until smooth. Divide batter between prepared pans and bake until a toothpick inserted in center comes out clean, 30 to 35 minutes. Cool in pans, 10 minutes. Remove from the pans and let cool completely on wire racks.
4. Combine egg whites, sugar, water, corn syrup, and salt in a mixing bowl over a saucepan of simmering water. Beat with an electric mixer on high until the icing stands up in soft peaks, about 6 to 8 minutes. Remove from heat, add vanilla, and beat 2 minutes more until frosting stands in stiff peaks.
5. Place 1 cake layer on a serving platter and spread with 1/3 of the frosting. Top with second layer and spread top and sides with remaining frosting. makes 12 to 16 servings.