Preheat oven to 350°F (180°C), then butter a 9.5 inch GoodCook Angel food cake pan.
Make the streusel topping: Mix together flour, brown sugar, cinnamon, and salt. Cut in butter using a pastry cutter or rub in with your fingers until small to medium clumps form. Mix in pecans.
For the Coffee Cake: On a stand mixer or using an electric hand mixer, beat butter and sugar on medium speed until pale and fluffy. Beat in eggs 1 at a time.
Add in the flour, baking powder, baking soda, salt, and sour cream and mix until just combined.
Spoon half the batter into the prepared angel food pan. Sprinkle 1/2 the streusel mixture evenly over batter. Top with remaining batter, and spread evenly using a spatula. Lastly, sprinkle remaining streusel topping evenly over the top.
Bake for 55 to 65 minutes or until cake is golden brown and a toothpick inserted into the center comes out clean.
While the coffee cake is baking make the glaze: In a small bowl whisk together the powdered sugar, milk, and maple syrup until you have a smooth shiny glaze.
Once the cake is baked remove it from the oven and transfer the pan to a wire rack, and let cool slightly. Remove from the pan and while the cake is still warm drizzle over the glaze.
Cover and store the coffee cake at room temperature for 3-4 days.