Preheat the oven to 355°F (180°C). Line a loaf pan with parchment paper, or spray it with baking spray.

In a large bowl, combine eggs and brown sugar. Whisk with a wire whisk until it thickens slightly and has a foamy top, about 30 seconds by hand.

Add the melted butter, pumpkin puree, Greek yogurt, vanilla extract, salt, and pumpkin pie spice into the batter and beat again.

Sift the flour, baking powder, and baking soda right into the same bowl. Stir or fold gently just until it forms a batter.

In a separate smaller bowl, carefully combine cocoa powder, boiling hot water, and espresso powder (optional). Whisk together carefully until it forms a smooth, thick, glossy mixture.

Divide the batter in half, transferring one of the halves into another bowl. Add the cocoa powder mixture into one of the halves and fold it in gently to create a chocolate batter. Fold the chocolate chips gently into the chocolate batter.

Alternate adding the batters into the loaf pan to create layers.

Bake the chocolate pumpkin loaf in the preheated oven for 55-60 minutes, or until a toothpick inserted into the center comes out clean.

Let the chocolate pumpkin loaf rest for 10 minutes in the pan before removing it and letting it cool the rest of the way.

Slice into it once it's at room temperature and serve!