• Preheat oven to 350F (175C) and thoroughly and generously grease and flour a bundt pan (tap out excess flour) or spray generously with baking spray (not cooking spray, it must contain flour or the cake will stick). Set aside.
• In a large bowl (or in the bowl of a stand mixer) whisk together flour, sugars, cocoa powder, cornstarch, baking soda, baking powder, and salt.
  2 cups (250 g) all-purpose flour, 1 cup (200 g) light brown sugar, 1 ½ cups (300 g) granulated sugar, ⅔ cup (68 g) natural cocoa powder, 1 Tablespoon cornstarch, ¾ teaspoon baking soda, ½ teaspoon baking powder, ¾ teaspoon salt
• Add butter and oil and stir well until completely combined (mixture will be thick).
  ½ cup (113 g) unsalted butter, ½ cup (118 ml) avocado oil or vegetable oil or canola oil
• Add eggs, egg yolk, sour cream, and vanilla extract and stir until smooth and well-combined.
  2 large eggs + 1 egg yolk, 1 ¼ cup (318 g) sour cream, 2 teaspoons vanilla extract
• Gradually add hot coffee or hot water and stir until combined. Stir in mini chocolate chips.
  ¾ cup (177 ml) hot coffee or hot water¹ , ½ cup (85 g) mini chocolate chips
• Pour batter into prepared bundt pan and bake on the center rack for 50-55 minutes or until a wooden skewer inserted in the thickest part of the cake comes out with a few fudgy crumbs or clean. Allow to cool for ten minutes then carefully invert onto a cooling rack to cool completely before covering with chocolate glaze.

Chocolate Glaze

• Combine chocolate, butter, and milk in a large microwave-safe bowl. Heat in 30 second increments (stirring well in between) until chocolate and butter are completely melted (mixture may look slightly separated, this is fine).
  3 oz (85 g) unsweetened chocolate, 4 Tablespoons unsalted butter, ⅓ cup (80 ml) whole milk
• Stir in vanilla and salt.
  ¼ teaspoon salt, 1 teaspoon vanilla extract
• Add powdered sugar and whisk until smooth. Allow to cool until mixture is still fluid but no longer runny (about 15 minutes) then drizzle over the top of the chocolate bundt cake. Allow glaze to harden before slicing and serving.
  2 cups (250 g) powdered sugar