1. Preheat oven to 325 degrees F. Spray a tube (9 1/2- or 10-inch diameter) or Bundt pan with vegetable cooking spray.
2. Prepare the cake. Stir chocolate in the top of a double boiler over simmering water until smooth. Remove from heat and set aside.
3. Sift the flour, baking powder, baking soda, and salt together in a medium bowl.Set aside.
4. Beat eggs and sugar in a large bowl using an electric mixer on medium speed until the mixture thickens and lightens in color, about 2 minutes. On low speed, slowly mix in the oil and vanilla. Add the flour mixture until incorporated. Mix in the yogurt until blended.
5. Remove 2 cups of batter and stir it into the melted chocolate until blended. Pour half the remaining vanilla batter into the prepared pan, spreading it evenly. Spoon the chocolate batter over it. Spread remaining vanilla batter evenly over the chocolate batter. Dip a butter knife in the batter and draw it around in a wave pattern to marbleize the batter.
6. Bake until a toothpick inserted in the center of the cake comes out clean, about 60 to 70 minutes. Cool for 15 minutes. Use a small sharp knife to loosen the cake from the sides and center tube of the pan. Place a wire rack on top of the cake and invert the cake onto the rack; leave the cake bottom side up for glazing. Cool to room temperature, about 1 hour, then transfer to a serving plate. Tuck waxed paper strips an inch under the bottom of the cake to keep the plate clean.
7. Prepare the vanilla glaze. In a small bowl, stir confectioners' sugar, 2 Tbsp. of the cream, corn syrup, and vanilla together until smooth, adding more cream if necessary. Cover with plastic wrap and set aside.
8. Prepare the chocolate glaze. In a saucepan over low heat, heat cream, butter, vanilla, and corn syrup until butter melts; stir to blend. Be sure mixture doesn't boil. Remove pan from heat and add chocolate. Let chocolate melt for about 30 seconds, then gently stir until all the chocolate melts and glaze is smooth.
9. Pour half the chocolate glaze over the cooled cake. Spread glaze inside the hole in the center and over the top of the cake. Spread remaining glaze over the sides.
10. Stir the reserved vanilla glaze. It should be pourable; if it has thickened, thin slightly with additional cream. Use a small spoon to drizzle about 4 tsp. of vanilla glaze over the top of the cake. Use the back of the spoon to gently swirl the vanilla and chocolate glazes. Gently pull out and discard the paper strips. Let cake set for 20 minutes before serving.
Source: Hannaford fresh Magazine, May - June 2013