Preheat the oven to 350 degrees F and line an 8" x 8" cake pan with parchment paper.

Add all ingredients for the pumpkin cake to a blender and blend until combined (note: you can also use a stand mixer or a mixing bowl with an electric mixer). Note: This batter will be very thick.

Stir together the ingredients for the pecan streusel topping in a bowl.

Spread half of the cake batter mixture into the prepared cake pan in an even layer. Sprinkle with half of the pecan streusel topping mixture. Repeat this for the remaining cake batter and pecan streusel topping, ensuring everything is spread into one even layer.

Bake on the center rack of the preheated oven for 30 to 40 minutes, until edges are golden brown. Remove coffee cake from the oven and allow it to cool 30 minutes before slicing and serving.