. Preheat the Oven: Preheat your oven to 350°F (175°C). Grease and flour a 9×9-inch baking wholesale cake boxes pan or a similar-sized baking dish.
2. Make the Streusel Topping: In a small bowl, mix together the brown sugar, ground cinnamon, and flour for the streusel topping. Cut in the cold butter pieces using a pastry cutter or fork until the mixture resembles coarse crumbs. Set aside.
3. Prepare the Cake Batter: In a medium-sized bowl, whisk together the flour, baking powder, baking soda, and salt. In a separate large mixing bowl, cream together the softened butter and granulated sugar until light and fluffy. Add the eggs one at a time, beating well after each addition. Stir in the vanilla extract. Gradually add the dry ingredients to the wet ingredients, alternating with the sour cream, beginning and ending with the dry ingredients. Mix until just combined.
4. Assemble the Cake: Spread half of the cake batter into the prepared baking pan. Sprinkle half of the streusel topping over the batter. Spoon the remaining cake batter on top and spread it evenly. Finish by sprinkling the remaining streusel topping over the top.
5. Bake the Cake: Bake in the preheated oven for 35-40 minutes or until a toothpick inserted into the center comes out clean, and the top is golden brown.
6. Make the Glaze: While the cake is baking, prepare the glaze. In a small bowl, whisk together the powdered sugar, milk, and vanilla extract until smooth. Adjust the consistency by adding more milk if needed.
7. Finish and Serve: Once the coffee cake is done baking, let it cool in the pan for about 10 minutes. Drizzle the glaze over the warm cake. Allow it to cool completely before cutting into squares and serving.
Enjoy your homemade delicious coffee cake with a nice cup of coffee or tea!