• Preheat oven to 350°F. Grease a 9x13-inch baking pan and set aside.

Prepare the Topping

• In a bowl, use a fork to combine the flour, brown sugar, cinnamon and butter. The texture should resemble coarse crumbs. Place in the refrigerator to chill while you make the batter and filling.
  1/2 cup all-purpose flour, 1/2 cup lightly packed brown sugar, 1 ½ teaspoons ground cinnamon, 5 tablespoons unsalted butter

Prepare the Batter

• In the bowl of a stand mixer fitted with the paddle attachment, or in a large bowl with an electric mixer, beat the butter and sugar on medium speed until light and fluffy. Add in the egg and mix until fully incorporated. Add in sour cream and vanilla and mix until combined.
  ½ cup unsalted butter, 1 cup granulated sugar, 1 large egg, 1 cup sour cream, 2 teaspoons pure vanilla extract
• In a large bowl, whisk together the flour, baking soda, baking powder, salt and cinnamon. Gradually add the dry ingredients to the wet ingredients in the mixer and mix until just combined. The batter will be very thick, almost like cookie dough.
  3 cups all-purpose flour, 1 teaspoon baking soda, 1 teaspoon baking powder, ½ teaspoon sea salt, 1 ½ teaspoons ground cinnamon
• Use a spatula or spoon to spread half of this batter into the prepared pan. If you find that you are having a hard time spreading it with a spatula or spoon, you can use clean, wet hands to press it into the pan. Set the other half to the side while you prepare the filling.

Prepare the Filling

• In the bowl of a stand mixer fitted with the paddle attachment, or in a large bowl with an electric mixer, beat the cream cheese, sugar, and vanilla until smooth. Add the egg and mix until incorporated. Use a spatula to spread the filling into the pan over the layer of batter.
  16 ounces cream cheese, ½ cup granulated sugar, 1 ½ teaspoons pure vanilla extract, 1 large egg
• Evenly drop the remaining batter onto the cream cheese filling by the spoonful. It doesn’t have to be perfect, just space the spoonfuls out as evenly as you can. Sprinkle the chilled topping evenly over the cake.
• Bake in the preheated oven for 45 minutes or until the top is golden brown. Remove the pan to a wire rack and let the coffee cake cool for 30 minutes before preparing the optional glaze.

For the Glaze

• In a small bowl, whisk together the powdered sugar, melted butter, vanilla, and milk. You want the glaze to be thin enough to drizzle over the cooled cake, but not watery. If the glaze is too thick after adding in the first tablespoon of milk, gradually add in a little more milk, ¼ teaspoon at a time until you reach the desired consistency. Drizzle topping over cooled cake.
  ½ cup powdered sugar, 1 tablespoon unsalted butter, ¼ teaspoon pure vanilla extract, 1 tablespoon milk