1. Preheat oven to 350 F. Spray an 8 ½” x 4 ½” loaf pan with non-stick cooking spray.
2. In a bowl, whisk together the flour, salt, baking soda, baking powder, and spices. Set aside.
3. In the bowl of a stand mixer, beat the oil and brown sugar together. Add the eggs one at a time, beating between each addition. Add the canned pumpkin, yogurt, and vanilla extract and beat into batter until smoothly and evenly incorporated. Add the dry ingredients to the wet and mix in at lowest speed just until evenly combined. Meanwhile, melt the 3 ounces of chocolate in a microwave-safe bowl, microwaving 30 seconds at a time and stirring every 30 seconds, until all chocolate has melted and is smooth.
4. Split the dough in half, keeping one half in the mixer and transferring the other half to a separate bowl or container. Add the melted chocolate and the cocoa powder to the stand mixer and mix in at lowest speed just until the batter is smooth or only has a few streaks of uneven color. Layer the two different batters into the prepared loaf pan, alternating between layers and smoothing out each layer before moving to the next. Once all batter has been added to the pan, use a knife to swirl the two batters around. Smooth the top of the batter with a spatula after swirling. (The colors on the top will start to blend, but this will be covered by the glaze).
5. Bake loaf in the preheated oven for 60-65 minutes, or until a toothpick inserted into the center comes out clean. Cool briefly (about 15 minutes), and then remove bread from pan and transfer to a wire rack to cool completely. Once cool, add the glaze.

To Make the Chocolate Ganache Glaze:

1. Combine milk and butter in a microwave-safe cup or bowl (preferably one with a pourable spout like a Pyrex measuring cup) and microwave for 10-15 seconds (stop if/when the milk starts to bubble up). Stir until the butter has melted into the milk. Add chocolate chips/chopped chocolate to the mixture and stir until the chocolate melts completely. This may take a minute or two, but if absolutely necessary, microwave for another 5 seconds only. Once the mixture is melted and smooth, slowly pour on top of the cooled loaf, aiming for the peak. Use a spatula to gently push the glaze down the peak, toward the edges of the loaf, as you pour. Allow the glaze to set; you can put the bread in the refrigerator if desired to speed up this process. Wrap loaf in plastic wrap or place in an airtight container and store in the refrigerator.