Preheat your oven to 350°F (175°C) and line a muffin or cupcake pan with liners.

In a small bowl, whisk together 1 cup of all-purpose flour, ½ teaspoon of baking soda, ¼ teaspoon of salt, and 1½ teaspoons of pumpkin spice until well combined.

In a medium or large bowl, mix together ¼ cup of canola oil and both sugars until smooth. Then, add the egg, ¾ teaspoon of vanilla extract, and ¾ cup of pumpkin puree, mixing well after each addition.

Fold the flour mixture into the wet ingredients gradually until no flour streaks are visible.

In a separate small bowl, whisk together another ¾ cup of all-purpose flour, 3 tablespoons of cocoa powder, ¼ teaspoon of baking soda, and a pinch of salt.

Mix in ½ cup of mini chocolate chips at this stage.

In a medium or large bowl, mix together ⅛ cup of canola oil and both sugars until smooth. Incorporate the egg, ¼ cup of sour cream, and 3 tablespoons of whole milk.

Fold in the dry ingredients into the wet mixture gradually until no flour streaks remain.

Layer the muffin liners: scoop spoonfuls of pumpkin batter and chocolate batter into each muffin liner until filled about ¾ full.

If desired, sprinkle the tops with an additional ¼ cup of mini chocolate chips.

Bake in the preheated oven for about 18–23 minutes, or until a toothpick inserted into the center comes out clean.

Allow the muffins to cool in the pan until comfortable to handle, then transfer to a wire rack to cool completely.