Preheat oven to 350 degrees F. Grease a 9-inch springform pan.
Sift together the flour, oats, baking powder, salt, and spices set aside.
In a medium bowl cream together the butter and 3/4 cup sugar and 1/4 cup brown sugar with an electric mixer. Add the eggs and mix in and add pumpkin puree.
Add the flour mixture to the wet ingredients and mix in. Spread into the prepared pan.
For the crumble mix together the 1/2 cup brown sugar, 1 teaspoon cinnamon, 1/4 teaspoon nutmeg, 1/4 teaspoon ginger, flour, old fashion oats, and walnuts. Add the butter and cut in until there are large crumbs that form.
Sprinkle over the top of the coffee cake. Place the coffee cake in the preheated oven for 30 to 32 minutes. Cool on wire cooling rack.