Marble Recipe

Preheat and prepare pan

Preheat the oven to 350°F (175°C). Grease and flour a 9-inch (23 cm) loaf pan or springform pan, or line a loaf pan with parchment paper, leaving an overhang for easy removal.

Combine dry ingredients

In a medium bowl, whisk together the all-purpose flour, baking powder, and salt until evenly distributed.

Cream butter and sugar

In a large mixing bowl, beat the softened unsalted butter and granulated sugar together with an electric mixer on medium speed until light and fluffy, about 2–3 minutes.

Add eggs and vanilla

Add the eggs one at a time, beating briefly after each addition until incorporated. Scrape down the bowl, then beat in the vanilla extract.

Alternate dry and wet

With the mixer on low, add about one-third of the dry flour mixture, then half of the milk. Continue alternating, ending with the remaining flour. Mix just until combined — do not overmix.

Prepare chocolate portion

In a small bowl, whisk the cocoa powder with the hot water to make a smooth paste. Scoop out about 1 1/4 to 1 1/2 cups of the batter (roughly one-third to half, depending on how prominent you want the chocolate) into the cocoa mixture and stir until the batter is evenly chocolate-colored.

Layer and marble

Spoon alternating dollops of the vanilla and chocolate batters into the prepared pan: start with a few tablespoons of vanilla batter in the center, add a few tablespoons of chocolate on top, and continue building concentric piles until all batter is used. Using a thin knife or skewer, swirl through the batter with a few gentle figure-eight motions to create a marble effect — do not over-swirl.

Bake

Smooth the top gently with an offset spatula. Bake in the preheated oven for 45–55 minutes, or until a toothpick or cake tester inserted into the center comes out with a few moist crumbs but no raw batter. If the top browns too quickly, tent loosely with foil after 30 minutes.

Cool

Remove from oven and allow the cake to cool in the pan for 10–15 minutes. Then use the parchment overhang or run a knife around the edges and transfer to a wire rack to cool completely before glazing or slicing.

Dust and glaze: If using powdered sugar, sift it over the cooled loaf just before serving. If using chocolate glaze, warm the glaze or melt the chocolate gently (microwave in 20-second bursts, stirring between) until smooth. Pour or spread the glaze over the cooled cake and let set for 15–20 minutes before slicing.