Preheat oven to 180 °C (350 °F) and grease and flour (or line with baking paper) 20x20 cm (8x8 inch) baking pan.
Make the streusel: In a small bowl, mix together all of the ingredients and place in the fridge while you make the cake.
Make the cake: Whisk the flour, baking powder, baking soda, salt, cinnamon and nutmeg together in a bowl. Set aside.
Whisk the eggs, oil, pumpkin, vanilla, brown sugar and granulated sugar until combined.
Fold in dry ingredients into wet ingredients using whisk or an electric mixer on the lowest speed, until completely combined. Batter will be thick.
Pour the batter into prepared pan and sprinkle the top with prepared streusel topping.
Bake for 35-45 minutes (depending on your oven). The cake is done when a toothpick inserted in the center comes out clean. If the top starts to brown to fast, loosely cover with aluminum foil.
Make the glaze: In a small bowl, whisk the cream cheese, powdered sugar, milk, vanilla and cinnamon until smooth. Drizzle over cooled cake.