Preheat the oven to 350 F (177 C). Lightly grease and line the bottom and two sides of a 9 x 9 inch (23 cm) cake pan with parchment paper.
In a medium bowl whisk the all purpose flour, baking powder and salt together until well combined.
1½ cups (180 g) all purpose flour, 1½ teaspoons baking powder, ¼ teaspoon salt
In a large mixing bowl, whisk the melted and slightly cooled butter, sugar, eggs, sour cream and vanilla extract until smooth and well combined. Alternating dry ingredients and milk, mix in ⅓ of the dry ingredients into the wet, followed by ½ of the milk. Repeat until all the ingredients are just combined. ½ cup (113 g) unsalted butter, melted and slightly cooled, 1 cup (200 g) granulated sugar, 2 large eggs, room temperature, ¼ cup (60 g) sour cream, room temperature, 2 teaspoons (10 ml) vanilla extract , ½ cup (118 ml) milk, room temperature
In a separate bowl whisk the sugar and ground sugar together until well combined. Gather the chocolate chips.
3 tablespoons (38 g) granulated sugar, 1 teaspoon ground cinnamon
Evenly spread half the cake batter into the prepared pan. Top the first layer of cake batter with half of the cinnamon sugar and chocolate chips. Repeat with a second layer of cake batter and finish with the remaining cinnamon sugar and chocolate chips.
1 cup (170 g) chocolate chips
Bake the vanilla and chocolate chip cake for 30 - 35 minutes or until a toothpick inserted into the center of the chocolate chip sour cream cake comes out clean or with a few moist crumbs.
Cool the pan in the pan for 15 - 20 minutes. Gently lift the chocolate chip cookie cake out of the pan using the parchment paper. Transfer to a serving plate or serve right from the pan.