Cream butter and sugar together until light and fluffy, then add eggs one at a time, mixing each egg in completely before adding the next. Stir in milk, vanilla and sour cream, then sift dry ingredients on top of wet ingredients and fold to combine. Cover and refrigerate for 1 hour.

In a separate mixing bowl, stir together the pumpkin, sugar, egg, cinnamon, ginger and nutmeg until completely combined.

In a third bowl, use a fork or your fingers to combine butter with sugar, flour, cinnamon, pecans and salt until butter is incorporated and mixture is crumbly. Refrigerate both until batter has rested.

About 30 minutes before assembling the coffee cake, place a rack in the center of the oven and preheat to 325 degrees. Spray a 9" x 13" baking dish with cooking spray and set aside.

Spread ½ the batter evenly into the bottom of the prepared baking dish then spread the pumpkin filling evenly over the top. Sprinkle about 1/3 cup of pecan streusel over top of the batter. Spread the remaining cake batter over the top and smooth into an even layer. Use a butter knife to gently swirl pumpkin mixture together with batter.

Sprinkle the remaining streusel evenly over the top. Bake 50–55 minutes, just until firm in the center. Remove to a rack to cool slightly, dust top with just a bit of powdered sugar, then slice and serve.