First Step: Preheat and Prepare Bakeware
Preheat the oven to 350°F (175°C). Grease and flour a 12-cup bundt pan or an equivalent metal baking pan to prevent sticking.

Second Step: Make the Streusel Filling
Combine ½ cup packed brown sugar, 1 teaspoon ground cinnamon, ¼ teaspoon pumpkin pie spice, and melted butter until crumbly. For a crunchier texture, mix in ¼ cup all-purpose flour and ½ cup chopped pecans if desired.

Third Step: Mix Dry Ingredients
In a large bowl, whisk together 3 cups all-purpose flour, 1 teaspoon pumpkin pie spice, 2 teaspoons cinnamon, 1 teaspoon baking soda, ½ teaspoon baking powder, and 1 teaspoon salt. This blend ensures the cake has a spiced, tender crumb.

Fourth Step: Cream Butter and Sugar
In a separate large bowl, beat 2 cups granulated sugar and 1 cup softened unsalted butter until light and fluffy. Add eggs one at a time, beating well after each addition to incorporate air for a lighter texture.

Fifth Step: Add Pumpkin and Sour Cream
Mix in 1 cup pure pumpkin puree, 1 cup sour cream, and 2 teaspoons vanilla extract until fully combined, which adds richness and moisture.

Sixth Step: Combine Wet and Dry Mixtures
Gradually add the dry ingredients to the wet mixture, beating until smooth but avoiding overmixing to keep the cake tender.

Seventh Step: Assemble Cake
Pour half the batter into the prepared pan, sprinkle the streusel filling evenly over the center portion, taking care to avoid the edges so the filling creates a visible layer. Top with the remaining batter, spreading it evenly.

Eighth Step: Bake and Cool
Bake the cake for 50 to 60 minutes or until a toothpick inserted in the center comes out clean or with a few moist crumbs. Cooling times may vary based on your pan material.

Final Step: Glaze and Serve
Allow the cake to cool in the pan on a wire rack for 30 minutes before inverting. Melt cinnamon chips with shortening in the microwave for one minute, stir smooth, and drizzle over the cooled cake. Alternatively, drizzle a maple syrup glaze before slicing.