- 4 tablespoons unsalted butter, at room temperature, plus more for the pan
- 1 1/2 cups all-purpose flour, spooned and leveled, plus more for the pan
- 6 ounces semisweet chocolate, chopped melted
- 1/4 cup plus 2 teaspoons canola oil
- 2 teaspoons ground cinnamon
- 1/2 teaspoon baking soda
- 1/4 teaspoon baking powder
- 3/4 teaspoon fine salt
- 1 cup sugar
- 1 cup pure pumpkin puree
- 2 large eggs, lightly beaten
- 1 teaspoon pure vanilla extract
- Heat oven to 350° F. Brush an 8 1/2-by-4 1/2-inch loaf pan with butter and dust with flour, tapping out the excess. Combine the chocolate and 2 teaspoons of the oil in a medium microwave-safe bowl. Microwave on high in 30-second intervals, stirring in between, until melted. Set aside to cool to room temperature.
- Whisk together the flour, cinnamon, baking soda, baking powder, and salt in a medium bowl; set aside.
- Beat the butter, sugar, and the remaining 1/4 cup oil in a large bowl with an electric mixer on medium-high until light and fluffy, 1 to 2 minutes. Add the pumpkin puree and mix until combined. Add the eggs, one at a time, and vanilla and mix until combined. Reduce mixer speed to low and slowly add the flour mixture. Mix until just combined.
- Transfer half the batter into the prepared pan. Top with two-thirds of the chocolate mixture. Repeat with the remaining batter and chocolate mixture. Using a skewer or a knife, swirl the chocolate and batter together to create a marbled pattern.
- Bake until a toothpick inserted in the center comes out clean, 50 to 60 minutes. Cool in the pan for 15 minutes. Transfer to a wire rack and let cool completely.