1. Preheat your oven to 350°F (175°C). Lightly grease and flour a 9×13 inch baking dish.
2. In a medium bowl, whisk together 2 ½ cups all-purpose flour, 1 ½ teaspoons ground cinnamon, ¼ teaspoon ground cloves, ½ teaspoon salt, 1 ½ teaspoons baking powder, and 1 teaspoon baking soda. Set aside.
3. In a large mixing bowl, combine 1 cup granulated sugar, ½ cup packed brown sugar, and ½ cup vegetable oil. Mix thoroughly.
4. Add 1 cup pumpkin puree and 1 teaspoon vanilla extract to the wet mixture. Mix until well incorporated.
5. Beat in the 2 large eggs one at a time, mixing well after each addition.
6. Gradually add the dry ingredient mixture to the wet ingredients. Mix on low speed until just combined. Do not overmix.
7. To make the streusel topping, combine ½ cup all-purpose flour, ½ cup packed brown sugar, and 1 teaspoon ground cinnamon in a medium bowl.
8. Add ½ cup cold butter (cut into small pieces) to the streusel mixture. Use a pastry blender or your fingertips to work the butter into the flour mixture until it resembles coarse crumbs.
9. Pour half of the cake batter into the prepared baking dish and spread it evenly.
10. Sprinkle half of the prepared streusel topping over the batter. Gently press it down.
11. Carefully spread the remaining cake batter over the streusel layer.
12. Sprinkle the rest of the streusel topping evenly over the top.
13. Place the dish in the preheated oven and bake for 45-55 minutes, or until a toothpick inserted into the center comes out clean.
14. Let the coffee cake cool completely on a wire rack.
15. For the optional glaze, whisk together 1 cup powdered sugar and 2-3 tablespoons milk or cream until smooth. Drizzle over the cooled coffee cake before serving.