Dark Chocolate–Orange Gingerbread Cake

Preparation

1. Cake

   Step 1

   Place a rack in middle of oven and preheat to 350°. Line bottom of an 8"-diameter cake pan with a parchment paper round. Lightly coat parchment and pan with nonstick vegetable oil spray or room-temperature unsalted butter. Whisk 1½ cups (188 g) all-purpose flour, 1 tsp. Diamond Crystal or ½ tsp. Morton kosher salt, ½ tsp. baking powder, and ¼ tsp. baking soda in a medium bowl. Mix ½ cup mild-flavored (light) molasses and ½ cup water in a measuring glass.

   Step 2

   Whisk ½ cup (packed; 100 g) dark brown sugar, ½ cup (1 stick) unsalted butter, room temperature, 1 Tbsp. finely grated ginger (from about a 3" piece), 1 Tbsp. finely grated orange zest (from 1 medium orange), 1 tsp. ground cinnamon, and ¼ tsp. freshly ground pepper in a medium bowl until light and creamy, about 5 minutes (if butter isn’t soft enough and mixture is hard to mix, smash butter with a rubber spatula at first to combine, then switch to the whisk). Add 1 large egg; whisk until emulsified, about 1 minute. Add dry ingredients in 3 additions, alternating with molasses mixture in 2 additions, beginning and ending with dry ingredients. Vigorously mix until combined, about 2 minutes (batter may look curdled and that’s okay).

   Step 3

   Scrape batter into prepared pan and smooth surface with a small offset spatula or a spoon. Bake until cake springs back when gently pressed, 40–45 minutes. Transfer pan to a wire rack and let cake cool in pan 10 minutes. Run offset spatula around sides of pan, then invert cake out onto rack and let cool completely.

2. Ganache and Assembly

   Step 4

   Place 3½–4 oz. 70% dark chocolate, chopped, in a medium bowl. Heat ½ cup heavy cream and ¼ tsp. Diamond Crystal or Morton kosher salt in a small saucepan over medium just until beginning to simmer; pour over chocolate. Let sit 2 minutes, then whisk gently until smooth. Let ganache cool until pourable, about 30 minutes. (Or, chill, stirring halfway through, until pourable, about 10 minutes.)

   Step 5

   Spoon ganache over cake (leave upside down; this will give you a nice flat top) and, using offset spatula, spread evenly over surface, letting some drip down sides. Let cake sit until ganache is fully set, about 30 minutes. (Or, chill about 10 minutes.) Transfer to a cake stand or platter to serve.

   Do Ahead: Cake can be baked 1 day ahead; store, airtight, at room temperature. Cake can be glazed 1 day ahead; store, covered with a cake dome or large bowl, at a cool room temperature.