Marble Cake

Place the butter in a mixing bowl.

Add the sugar to the butter and mix until the mixture becomes smooth and creamy.

Add the vegetable oil and mix well until combined.

Gradually add the eggs while continuing to beat.

Add the vanilla and mix all the wet ingredients until fully combined.

Gradually add the flour along with the baking soda and baking powder, then gently fold until no traces of flour remain.

Add the sour cream and mix until the batter becomes smooth and well combined.

Divide the batter into two equal parts.

Add the cocoa powder to one part and mix until fully colored.

Grease the bundt pan with butter and dust it lightly with flour to prevent sticking.

Alternately add scoops of the chocolate batter and the plain batter into the pan using an ice cream scoop.

Use a wooden skewer to swirl the batter and create the marble effect.

Bake the cake in a preheated oven at 180°C (350°F) for 45 minutes or until a toothpick inserted in the center comes out clean.

Remove the cake from the oven and let it cool completely.

Pour chocolate sauce over the cooled cake and serve.