Marble cake with chocolate glaze

Ingredients:

Cake

• 110 g semi-sweet chocolate, finely chopped
• 3 cups premium flour
• 2 tsp baking powder
• 1 teaspoon of baking soda
• 1 teaspoon coarse salt
• 1 and 3/4 cups granulated sugar
• 220 g unsalted butter, room temperature
• 1/4 cup canola oil
• 1 tbsp vanilla extract
• 3 large eggs, room temperature
• 1.5 cups whole milk

Glazes

• 110 g unsalted butter, room temperature
• 2/3 cup cocoa powder
• 1/4 cup heavy cream + more as needed
• 2 tsp vanilla extract
• 0.5 tsp coarse salt
• 2 and 3/4 cups powdered sugar + more as needed

Preparation:

1. Position a rack in the middle of the oven and preheat the oven to 350°F (175°C). Spray a 9 x 13-inch baking pan with cooking spray and line the bottom with parchment paper.
2. Place the chocolate in a medium microwave-safe bowl and heat in 20-second intervals, stirring, until completely melted. Set aside.
3. In a medium bowl, whisk together the flour, baking powder, baking soda, and salt and set aside. In a large bowl, beat the sugar, butter, and vegetable oil with a mixer on medium-high speed until light and fluffy, about 4 minutes. Reduce the mixer speed to low and add the vanilla extract. Then beat in the eggs one at a time, scraping down the sides of the bowl with a spatula and mixing well after each addition.
4. Add one-third of the flour mixture and mix on low speed until completely incorporated. Add half of the milk and mix until smooth. Repeat alternating the flour mixture and milk, scraping down the sides of the bowl after each addition, and mix until the last of the flour is completely incorporated.
5. Place a quarter of the dough into the bowl with the melted chocolate and stir until smooth.
   
   
   When measuring flour, spoon it into a dry measuring cup and remove any excess. Scooping flour directly from the bag with a measuring cup will compact it, resulting in dry baked goods.
6. Pour half of the remaining vanilla batter into the prepared pan and smooth it out to the edges with an offset spatula. Using a large spoon, spoon mounds of chocolate batter onto the vanilla batter, then pour the remaining vanilla batter on top. Insert a wooden skewer or butter knife into the batter and swirl the chocolate batter into the vanilla batter to create a marbled pattern.
7. Bake, rotating the pan halfway through, until a toothpick inserted into the center comes out clean, about 35 minutes. The top of the cake should feel springy to the touch and the vanilla spots are light golden. Cool the cake in the pan for 10 minutes, then run a knife around the edges to loosen them from the pan and invert the cake onto a wire rack to cool completely before frosting.
8. Glaze:
   
   In a medium bowl, beat the butter with a mixer on medium speed until smooth, about 3 minutes. Add the cocoa powder, cream, vanilla, salt, and 1.5 cups powdered sugar and mix on low speed until fully incorporated. Mixing on low speed, gradually add the remaining powdered sugar until fully incorporated. Increase the mixer speed to medium-high and beat until the frosting is light and fluffy, about 2 minutes; the frosting will lighten in color as it incorporates air (see Note).
   
   
   The consistency of the glaze can be adjusted as needed by adding more cream (if it is too thick) or powdered sugar (if the glaze is too thin), 1 tablespoon at a time.
9. Using a spatula, spread the glaze in a thick layer over the entire surface of the cooled cake.