Zebra Marble Hazelnut Loaf Cake with Roasted Hazelnut Crown Step-by-step instructions

Before you start

Heat the oven to 340°F (171°C) and position a rack in the center. Line a 9x5-inch loaf pan with parchment paper, leaving overhang on the long sides for easy removal.

Gather all ingredients and measure them out. The eggs should be at room temperature for better volume when whisked. If the hazelnuts are not already roasted, toast them first and let cool before chopping.

Instructions

Build the Batter

1. 1Whisk the Wet Base
   In a large bowl, whisk the eggs and granulated sugar together until pale and frothy, about 2 minutes. Add the vegetable oil, whole milk, and vanilla extract, and whisk until combined. The mixture should be smooth and glossy.
   Look for The mixture turns pale and slightly thickened, with small bubbles on the surface.
   Tip Whisk vigorously to incorporate air for a lighter crumb.
2. 2Add the Dry Ingredients
   Add the all-purpose flour and baking powder to the wet mixture. Whisk just until no dry streaks remain, forming a smooth, glossy batter. Do not overmix.
   Look for The batter is smooth, thick, and lump-free.
   Tip Overmixing develops gluten and makes the cake tough.

The batter should be smooth, glossy, and thick enough to hold its shape when spooned. The egg-sugar mixture should be pale and frothy, with tiny bubbles. After adding the flour, the batter should be lump-free but not overmixed. The chocolate batter should be a deep, even brown.

Create the Zebra Pattern

3. 3Divide and Color the Batter
   Divide the batter evenly between two bowls. Into one bowl, whisk in the dark cocoa powder until fully incorporated. The other bowl remains the vanilla batter.
   Look for The chocolate batter is a deep, rich brown with no streaks.
   Tip Fold the cocoa gently to avoid deflating the batter.
4. 4Layer the Batters in the Pan
   Line a 9x5-inch loaf pan with parchment paper. Spoon alternating dollops of vanilla and chocolate batter into the pan, creating a checkerboard pattern when viewed from above. Use a spoon or knife to drag gently through the batter to create zebra swirls.
   Look for The pan is filled with distinct light and dark patches.
   Tip Drag the spoon in a zigzag motion for dramatic swirls.
5. 5Top with Hazelnuts
   Evenly shower the top of the batter with the chopped roasted hazelnuts, pressing them in lightly so they adhere during baking.
   Look for The entire surface is covered with hazelnut pieces.
   Tip Press gently so the nuts don't sink into the batter.

As you spoon alternating dollops of batter into the pan, the layers should stay separate, forming a checkerboard pattern when viewed from above.

Dragging a spoon through the layers should create distinct, wavy swirls without fully mixing the colors. The top should be evenly covered with hazelnuts.

Bake and Finish

6. 6Bake the Loaf
   Bake in an oven preheated to 340°F (171°C) for 40 minutes, until the cake is tall, cracked down the center, and golden brown. A toothpick inserted into the center should come out clean.
   Look for The top is deeply golden, the center springs back when pressed, and a crack runs down the middle.
   Safe temperature 160°F (71°C) internal temperature (egg dishes)
   Tip Rotate the pan halfway through for even browning.
7. 7Cool and Slice
   Remove the loaf from the oven and let it cool in the pan for 10 minutes. Then transfer to a wire rack to cool completely before slicing. Use a serrated knife for clean, even slices.
   Look for The loaf is firm to the touch and releases cleanly from the pan.
   Tip Cooling completely prevents crumbling when slicing.

The loaf should rise tall with a cracked, golden top. The hazelnuts will toast and become fragrant. The cake should feel springy when pressed, and a toothpick should come out clean. After cooling, the slices should show clear zebra stripes.

Common mistakes

A common mistake is overmixing the batter after adding the flour, which develops gluten and makes the cake dense and tough. Stop whisking as soon as the flour disappears.

Another issue is overfilling the pan with too much batter, which can cause the cake to overflow during baking. Use the specified 9x5-inch pan. Finally, if the top browns too quickly, tent loosely with foil for the last 10 minutes.

How to tell it’s done

The cake is done when the top is deeply golden and a crack has formed down the center. The center should spring back when pressed gently, and a toothpick inserted into the middle should come out clean or with just a few moist crumbs.

The internal temperature at the center should reach at least 160°F (71°C) to ensure the eggs are fully cooked. Let the loaf cool in the pan for 10 minutes, then transfer to a rack to cool completely before slicing.

• Egg dishes: 160°F (71°C) in the thickest part