Preheat your oven to 350°F (175°C) and prepare an 8x8-inch baking dish by greasing it with butter or lining it with parchment paper.

In a mixing bowl, whisk melted butter and light brown sugar until smooth, then add the egg and pumpkin puree, stirring until well combined.

In a separate bowl, mix flour, baking soda, baking powder, cinnamon, nutmeg, and salt until well blended.

Gently fold the dry ingredients into the wet mixture until just combined, ensuring the batter remains moist.

Stir in the chocolate chips until evenly distributed in the batter, being careful not to overmix.

Transfer the batter to the prepared baking dish, spreading it evenly with a spatula.

Mix granulated sugar and cinnamon in a bowl, then sprinkle it over the batter for a sweet crust.

Bake in the preheated oven for 30-35 minutes until the edges are golden and a toothpick comes out clean.

Let the cake cool in the pan for 15 minutes before slicing and serving warm or at room temperature.