Preheat the oven to 350°F (175°C) and line a muffin tin with cupcake liners.
In a large mixing bowl, whisk together the flour, sugar, cinnamon, nutmeg, baking powder, baking soda, and salt until evenly combined. This creates a flavorful dry mix that will give the muffins their autumnal warmth.
In a separate bowl, whisk the eggs, pumpkin puree, and vegetable oil until smooth and slightly frothy. The mixture should be uniform in color and texture, with no streaks.
Pour the wet mixture into the dry ingredients and gently fold with a spatula until just combined. Be careful not to overmix; the batter should be slightly lumpy but well incorporated.
Fold in the chocolate chunks and toasted walnuts, distributing them evenly throughout the batter. The chocolate will start to melt slightly, creating pockets of decadence.
Divide the batter evenly among the prepared muffin cups, filling each about two-thirds full. This ensures room for the muffins to rise and expand during baking.
Bake in the preheated oven for 18-20 minutes, or until the tops are golden brown and a toothpick inserted into the center comes out clean.
Remove the muffins from the oven and let them cool in the tin for a few minutes before transferring to a wire rack to cool completely. The tops should have a slight crumble and a tender crumb inside.
Once cooled, enjoy these moist, pumpkin-infused muffins with melted chocolate and crunchy walnuts in every bite. They’re perfect for a cozy fall treat or a quick breakfast.
