One times the chocolate just wasn’t going to cut it.
1/2 c. butter, melted, plus more for buttering pan
1 c. all-purpose flour
1/2 c. cocoa powder, plus more for dusting pan
1 tsp. baking soda
1/2 tsp. baking powder
1/4 tsp. kosher salt
3/4 c. sugar
1/4 c. sour cream
1 tsp. vanilla extract
1 large egg, plus 1 large egg yolk
2 1/2 c. semisweet chocolate chips
1 c. pumpkin puree (unsweetened)
3/4 c. heavy cream
Preheat oven to 350 degrees F. Butter a 9-x-5″ loaf pan and dust with cocoa powder.
In a large bowl, whisk together flour, cocoa powder, baking soda, baking powder, and salt.
In another large bowl, combine melted butter, sugar, sour cream, vanilla, egg and egg yolk until smooth. Pour wet ingredients over dry and stir until combined, then fold in 1 cup chocolate chips and pumpkin puree.
Transfer batter to prepared pan and bake until a toothpick comes out clean, 55 to 65 minutes. Let cool at least 10 minutes.
Make ganache: Place remaining 1 1/2 cups chocolate chips in a heatproof bowl. In a small saucepan over low heat, heat heavy cream just until it bubbles. Pour heavy cream over chocolate chips and let stand 2 minutes. Whisk until completely smooth and no clumps remain.
Pour ganache over pumpkin bread, smoothing top if desired, and serve.