Prep the Pan - Preheat your oven to 350°F (175°C). Grease or spray a 9x13-inch (33x23 cm) baking dish with non-stick spray.
Make the Streusel - In a medium bowl, whisk together the brown sugar, granulated sugar, cinnamon, and salt. Pour in the melted butter and stir until smooth. Add the flour and mix until crumbly and well combined. Set aside.
¾ cup brown sugar, ⅓ cup granulated sugar, ½ teaspoon salt, 4 teaspoons ground cinnamon, ¾ cup unsalted butter, 2 cups unbleached all-purpose flour
Mix the Dry Ingredients - In a large bowl, whisk together the flour, baking soda, baking powder, pumpkin pie spice, and salt.
3 cups unbleached all-purpose flour, 1 ½ teaspoons baking soda, 1 ½ teaspoons baking powder, 1 tablespoon pumpkin pie spice, ½ teaspoon salt
Cream the Butter and Sugars - In a separate large mixing bowl, beat the room-temperature butter with both sugars until light and fluffy, about 2–3 minutes.
1 cup brown sugar, 1 cup butter, ½ cup granulated sugar
Add the Eggs and Pumpkin - Beat in the eggs one at a time, then add the pumpkin puree and mix until fully incorporated. The batter may look slightly curdled at this stage, but it will come together once the dry ingredients are added. Note: A 29 oz can (822g) will also work.
2 large eggs, 2 cans pumpkin puree
Bring the Batter Together - Add the dry ingredients to the wet mixture in two additions, stirring gently after each until just combined. Do not overmix.
Assemble the Cake - Spread half of the batter evenly into the prepared pan. Sprinkle with half of the streusel mixture. Spread the remaining batter on top, then finish with the rest of the streusel.
Bake - Bake for 45–50 minutes on 350°F (175°C), or until a toothpick inserted in the center comes out clean. If the streusel browns too quickly, loosely tent the pan with foil.
Drizzle and Serve - In a small bowl, whisk together the powdered sugar and milk until smooth. Drizzle over the cooled cake before slicing.
½ cup powdered sugar, 1 tablespoon milk
Bite Me Tip: This cake tastes even better the next day once the pumpkin and spice flavors settle in. Seal with an air tight cover and store at room temperature for up to 3 days, or freeze slices for a cozy treat anytime.