Special equipment: a 6-cup bundt pan (about 8 inches in diameter)
Preheat the oven to 350 degrees F.
For the streusel: Pulse together the sugar, flour, pecans, butter, cinnamon and salt in a food processor until a nubby dough starts to form. Transfer to a sheet tray lined with parchment paper and break apart into chickpea-size pieces. Chill in the refrigerator for one hour.
For the coffee cake: Cream the butter, sugar and vanilla in a stand mixer fitted with the paddle attachment until the mixture is smooth and fluffy (this can also be done with a hand mixer). Add the eggs, one at a time, scraping down the bowl with a rubber spatula after each addition.
Whisk together the flour, baking powder, baking soda and salt in a medium bowl.
Add the flour mixture to the butter mixture in 3 batches, alternating with the sour cream.
Spray a bundt pan with cooking spray. Pour half the batter into the pan and spread it out using the back of a spoon. Sprinkle the streusel on top of the batter (it will seem like a lot of streusel, but that's normal). Cover the streusel with the remaining batter. Bake the coffee cake until a toothpick comes out clean, about 50 minutes.
Allow the cake to cool completely before unmolding.
Whisk together the confectioners¿ sugar and milk until glossy and slightly thick (it should easily drop from the whisk). If the icing is too thick add a few more drops of milk until the desired consistency is reached.
With the tip of a small whisk or spoon generously drizzle the cooled cake with the icing. Before the icing sets, sprinkle the cake with the pecans.
This recipe was provided by a chef, restaurant or culinary professional. It has not been tested for home use.