Cake o' the Week: Chocolate Marble Gooey Butter Cake

I'm heading to a Women's Retreat with some friends from work, so I thought I would bake a cake to take along.

*Warning:  This cake is not for the faint-of-heart.  Seriously, it has a lot of butter in it, so if you have heart issues, you probably shouldn't eat it.  

Ingredients

Crust
1 package (18.25 oz) plain yellow cake mix
1 stick (8 tablespoons) butter, melted
1 large egg

Filling
1 package (8 oz) cream cheese, at room temperature
2 large eggs
1 teaspoon pure vanilla extract
1 stick (8 tablespoons) butter, melted
3 3/4 cups confectioners' sugar, sifted
1 package (6 oz.; 1 cup) semisweet chocolate chips

Baking

1.  Place rack in the center of the oven and preheat the oven to 350 degrees.  Set aside an ungreased 13- by 9- inch baking pan.

2.  For the crust, place the cake mix, melted butter, and egg in a large mixing bowl.  Blend with an electric mixer on low speed for 2 minutes.  Stop the machine and scrape down the side of the bowl with a rubber spatula.  The batter should come together in a ball.  With your fingertips, pat the batter evenly over the bottom of the pan, smoothing it out with your fingers until the top is smooth.  Set the pan aside.

3.  For the filling, place the cream cheese in the same mixing bowl that was used to make the crust, and with the same beaters (no need to clean either), blend with an electric mixer on low speed until fluffy, 30 seconds.  Stop the machine and add the eggs, vanilla, and melted butter and beat on medium speed for 1 minute.  Stop the machine and add the confectioners' sugar.  Beat on medium speed until the sugar is well incorporated, 1 minute more.  Stop the machine and scrape down the sides of the bowl with a rubber spatula.

4.  Place the chocolate chips in a small saucepan over low heat.  Cook, stirring until the chips are melted, 1 to 2 minutes.  Measure out 1 cup of the cream cheese filling and fold it into the chocolate mixture, stirring so the batter becomes well combined and all one color.  Set aside.

5.  Pour the remaining filling on the crust and spread with the rubber spatula so that the filling covers the entire surface and reaches the side of the pan.  Drop spoonfuls of the chocolate batter over the top of the filling, then swirl them with a dinner knife so the top of the batter has a marbled effect.  Be careful not to cut through the crust.  Place the pan in the oven.

6.  Bake the cake until it is well-browned but the center still jiggles when you shake the pan, 25 to 45 minutes.  Remove the pan from the oven and place it on a wire rack to cool, 30 minutes.  Cut into squares and serve.

*Store this cake, covered in aluminum foil, at room temperature for up to 4 days or in the refrigerator up to 1 week.  Or freeze it, wrapped in foil, for up to 6 months.  Thaw the cake overnight in the refrigerator before serving.