Step 1

For Streusel Topping: Add sugar, flour, butter and lemon zest in a small bowl and stir using a fork or pastry blender until the texture resembles coarse cornmeal, with the butter pieces no larger than small peas. Transfer mixture to the refrigerator until ready to use.

Step 2

Adjust oven rack to middle position and heat oven to 350 degrees.

Step 3

Spray a 9” x 13” cake pan with nonstick cooking spray.

Step 4

For the Cake: Whisk flour, baking powder, baking soda, and salt together in medium bowl; set aside.

Step 5

In stand mixer fitted with paddle attachment, beat butter, sugar, and lemon zest at medium speed until light and fluffy, about 3 minutes, scraping down sides and bottom of bowl with rubber spatula. Add eggs 1 at a time, beating well after each addition, about 20 seconds, and scraping down beater and sides of bowl as necessary. Add vanilla and mix to combine. Reduce speed to low and add one-third flour mixture, followed by half of sour cream, mixing until incorporated after each addition, 5 to 10 seconds. Repeat, using half of remaining flour mixture and all of remaining sour cream. Scrape bowl and add remaining flour mixture; mix at low speed until batter is thoroughly combined, about 10 seconds. Remove bowl from mixer and fold batter once or twice with rubber spatula to incorporate any remaining flour.

Step 6

Reserve half of the batter and set aside. Spoon remaining batter into prepared pan and smooth top.

Step 7

To make the Filling: Return now-empty bowl to mixer and beat cream cheese, sugar, lemon juice, vanilla and egg on medium speed until smooth, about 1 minute. Add ¼ cup reserved batter and mix until incorporated. Spoon cheese filling mixture evenly over batter and smooth the top. Spread remaining reserved batter over filling and smooth top. With butter knife or offset spatula, gently swirl filling into batter using figure-8 motion. Firmly tap pan on counter 2 or 3 times to dislodge any bubbles. Sprinkle streusel topping evenly over batter.

Step 8

Bake until just firm and skewer inserted into cake comes out clean (skewer will be wet if inserted into cheese filling), 35 to 40 minutes. Cool cake in pan on wire rack 1 hour. Gently remove from cake pan and place on wire rack to cool to room temperature, about 1½ hours.

Step 9

To make the lemon drizzle, in a small bowl, whisk together the confectioners’ sugar and ½ tablespoon of the lemon juice. The mixture should be thick but pourable. Add up to another ½ tablespoon of lemon juice if the mixture is too stiff. Drizzle over the top the coffee cake. Let harden, about 10 minutes, before serving.