In a stand mixer combine the flour, brown sugar and salt. Add the 1/2 cup butter and blend well.
Measure out 2/3 cup of the mixture into a separate bowl to make the streusel. Add the 3 tablespoons sugar and pumpkin spices to this separate bowl, blend and set aside.
Add the baking soda, pumpkin, sour cream and eggs to the flour mixture left remaining in your mixer. Blend until smooth, about 2 minutes.
Layer the cake batter, then the sautéed apples and finally sprinkle the streusel over the top.
Bake, uncovered, for about 1 hour. Allow to cool in the pan and then remove the springform. Serve with Vanilla ice cream and an apple chip.