Preheat your oven to 350°F. Line an 8x8-inch square baking pan with parchment paper, allowing the paper to hang over the sides about 2 inches for easy removal.

Make the crumb topping. Combine the flour, chopped pecans, brown sugar and salt in a bowl so it is evenly blended. Add cooled melted butter and rub it in evenly until it forms soft crumbs. Cover the bowl and set aside.

Make the cinnamon sugar swirl mixture. Combine brown sugar, cinnamon, cardamom and cocoa powder in a small bowl and set aside.

Make the pumpkin batter. Combine flour, spices, baking powder, baking soda, and salt in a medium bowl and whisk to blend evenly. Combine pumpkin puree, sour cream, brown sugar, oil, egg and vanilla in a large bowl and whisk until smooth. Add the dry ingredients and gently fold them in using a rubber spatula.

Spread two-thirds of the batter evenly into the pan. Sprinkle the cinnamon sugar evenly over top to cover it entirely. Dollop remaining batter on top and then gently spread it out evenly. Crumble the topping over the batter in an even layer.

Bake for 35-40 minutes until a toothpick inserted into the center comes out clean. Transfer the pan to a wire rack and let cool completely. Once cooled, drizzle with salted caramel sauce and sprinkle some pepitas on top if desired.