1-Preheat your oven: Start by preheating your oven to 350°F to ensure even baking.

2-Whisk dry ingredients: In a small bowl, whisk together the dry ingredients: 2 cups all-purpose flour, 1 ½ teaspoons baking powder, ½ teaspoon salt, 1 ½ teaspoons ground cinnamon, and 2 teaspoons pumpkin pie spice.

3-Cream wet ingredients: In another bowl, cream ½ cup softened unsalted butter with 1 cup light brown sugar and ¼ cup granulated sugar until fluffy. Add 1 large egg at room temperature, ⅓ cup whole milk, and 1 teaspoon vanilla extract, beating until smooth, then mix in ½ cup canned pumpkin purée.

4-Combine mixtures: Gradually combine the dry mixture with the wet one, stirring just until blended to avoid a dense texture.

5-Prepare the pan and streusel topping: Spread the batter into a greased 9×9 inch pan. For the streusel, mix ½ cup light brown sugar, ½ cup all-purpose flour, and ½ teaspoon ground cinnamon, then add ¼ cup cold cubed unsalted butter and blend until crumbly. Sprinkle this over the batter.

6-Bake the cake: Bake for 27 to 32 minutes, or until a toothpick comes out clean.

7-Cool and prepare icing: After baking, let it cool for 10 minutes. Prepare the icing by mixing 1 cup powdered sugar, 1 teaspoon melted butter, 1 to 2 tablespoons milk, and ½ teaspoon vanilla extract to your desired consistency, then drizzle it over the cake.

8-Serve and store: Serve warm or at room temperature, and store in an airtight container for 2-3 days at room temperature or 5-7 days refrigerated.