Snickerdoodle Cake with Streusel Topping

Preheat the oven to 350 degrees F (175 degrees C). Grease a 9x13-inch baking pan.

Mix 2 tablespoons white sugar and 2 teaspoons cinnamon together and sprinkle 1/2 of the mixture into the bottom of the greased baking pan. Save remaining 1/2 and set aside for sprinkling over cake batter.

Cream together sugar, butter, and vanilla extract with an electric mixer in a large bowl. Add eggs; mix to combine.

Sift together all-purpose flour, cinnamon, baking powder, and salt in a separate bowl. Stir into the egg mixture in batches, alternating with milk.

Pour batter into the prepared baking pan. Sprinkle with reserved cinnamon and sugar mixture. Set aside.

Mix brown sugar and cake flour together in a bowl until well combined. Cut in butter using a pastry blender; work mixture until crumbly to create streusel. Sprinkle streusel on top of cake.

Bake in the preheated oven until a toothpick inserted into the center comes out clean, 35 to 40 minutes. Let cool completely before serving.