Preheat: Preheat your oven to 400°F (200°C), with the heat on the bottom rack only.

Prep: Grease and flour an 8×4 inch loaf pan.

Wet Ingredients: In a large bowl, whisk together the eggs, brown sugar, melted butter, milk, pumpkin puree, and vanilla extract until combined.

Dry Ingredients: In a separate bowl, whisk together 105g of flour, baking soda, baking powder, and pumpkin pie spice.

Combine: Gradually add the dry ingredients to the wet ingredients, mixing until just combined.

Chocolate Swirl: Remove half of the batter and stir in the cocoa powder.

Layer: Spoon one-third of the pumpkin batter into the prepared loaf pan. Top with one-third of the chocolate batter. Repeat until all the batter is used, ending with a layer of pumpkin batter.

Bake: Bake for 10 minutes at 400°F (200°C), then reduce heat to 350°F (180°C) and bake for an additional 30 minutes. If the top is browning too quickly but the cake is still undercooked, reduce the heat to 325°F (160°C) and continue baking.

Test: Insert a toothpick into the center of the cake. If it comes out clean, the cake is done. Baking times may vary, so check after 40 minutes.

Cool: Let the cake cool completely in the pan before slicing.