Preheat your oven to 350°F and lightly grease a 9x9 inch baking pan. Place parchment paper in the pan for easy removal later on.

In a large bowl, whisk together the all-purpose flour, granulated sugar, pumpkin pie spice, baking powder, baking soda, and salt until well combined and fluffy.

In a separate medium bowl, mix the pure pumpkin puree, oil, egg, yogurt, and vanilla extract until the mixture is smooth and creamy.

Gently fold the wet ingredients into the dry ingredients using a spatula until just combined. Reserve ½ cup of this batter and stir in the espresso powder.

Pour the pumpkin batter into the prepared pan. Spoon dollops of the espresso batter on top and swirl them together using a knife. Bake for 20-25 minutes.

After baking, let the cake cool in the pan for about 20 minutes. Then, transfer it to a wire rack to cool completely.

In a small bowl, dissolve the light brown sugar in brewed espresso and light cream. Poke several holes in the cooled cake and brush the soak evenly over the top.

In a large mixing bowl, beat the unsalted butter until fluffy. Gradually add the powdered sugar, heavy cream, and espresso powder, mixing until smooth.

Once the cake is completely cooled, spread the espresso buttercream frosting evenly over the top. Drizzle with reserved espresso syrup and sprinkle with cinnamon.