Preheat the oven to 350ºF (180ºC). Line the bottom of a 9 x 5-inch loaf pan with parchment paper. Grease and flour the insides with a mixture of equal parts unsweetened cocoa powder and flour.

In a medium-size bowl, whisk together the flour, pumpkin pie spice, baking powder, baking soda and salt until well combined.

Set aside one tablespoon (15ml) of the oil. In a large bowl, beat the remaining oil, the sugar, brown sugar, eggs, evaporated milk and vanilla extract until smooth and well combined. Beat in the pumpkin purée until incorporated. Stir in the flour mixture just until combined.

Place one cup (237g) of the batter in a separate medium-size bowl. Add the cocoa powder, espresso powder and the reserved one tablespoon of oil. Mix until incorporated.

Place half of the pumpkin batter into the baking pan. Scoop the mocha batter into the pan, alternating with scoops of the remaining pumpkin batter. Swirl the batter with a skewer. Bake until a toothpick inserted into the center comes out clean or with a few moist crumbs attached (not wet batter), about 35-45 minutes. Let the loaf cool in the pan for 10 minutes, then turn the loaf out and continue cooling on a cooling rack.

Melt the butter, chocolate, and corn syrup together in a medium-size heatproof bowl set over a pan of barely simmering water, making sure the water doesn’t touch the bottom of the bowl. Stir gently until smooth. Set aside to cool slightly then spoon the glaze over the cooled loaf and let it drip down the sides.