In this weekly series, home cook Bruce Watson works his way through a decades-old family cookbook, adapting the best recipes exclusively for Slashfood.

When I came across a recipe for "Swiss Squares" in my family's cookbook, I got excited. Although the dish seemed like a basic chocolate cake recipe, it used sour cream for leavening. As this is a pretty uncommon choice, I wanted to see its effect on the product.

Overall, I found that the bars were a bit richer than expected, with a nice moist crumb. In my finished version, I massively increased the chocolate and dolled up the frosting. Still, at its heart, this is a recipe for a rich chocolate cake. Then again, even the simplest cake can be pretty profound!

Get the Swiss squares recipe after the jump.

Quadruple-Chocolate Swiss Squares

9 tablespoons butter, divided
6 ounces unsweetened Baker's chocolate, divided
1 cup flour
1 cup sugar
1 egg
1/4 cup sour cream
1/2 teaspoon baking soda
1/4 teaspoon salt
2 tablespoons milk
2 cups powdered sugar
1 teaspoon vanilla
3 tablespoons Mozart Black liqueur

Preheat oven to 375 degrees F. Chop up 4 tablespoons butter and 3 ounces Baker's chocolate and bring to a simmer in a small saucepan over medium-high heat. When mixture begins bubbling around the edges, quickly remove from heat and allow to cool slightly.

In a medium-sized mixing bowl, combine chocolate mixture, flour, sugar, egg, sour cream, baking soda and salt. Blend thoroughly, but do not overmix. Pour into a 9-inch square pan that has been buttered and floured. Bake for 20 minutes to 30 minutes, or until a toothpick inserted in the center comes out clean. Allow to cool.

Chop up 4 tablespoons butter and 3 ounces Baker's chocolate and bring to a simmer in a small saucepan over medium-high heat. When mixture begins bubbling around the edges, quickly remove from heat and allow to cool slightly. In a mixing bowl, combine with vanilla, Mozart liqueur, milk and remaining tablespoon of butter.

Using a hand mixer, combine ingredients, adding powdered sugar, 1/4 cup at a time, until frosting has reached a smooth, spreadable consistency (you do not have to use all the sugar). When finished, frost the cake and serve.