Step 1

Arrange a rack in the middle of the oven and heat the oven to 325°F. Lightly coat a 9x13-inch baking pan with cooking spray.

Step 2

Place 1 cup packed dark brown sugar and 1 tablespoon ground cinnamon in a small bowl and stir to combine.

Step 3

Place 1 box yellow cake mix, 8 ounces sour cream, 3/4 cup vegetable oil, and 4 large eggs in a large bowl and whisk until smooth, about 1 minute. Pour half of the cake batter into the prepared pan and spread evenly to the edges. Sprinkle evenly with the brown sugar and cinnamon mixture.

Step 4

Carefully spoon the remaining cake batter over the sugar layer and spread it evenly to the edges of the pan.

Step 5

Bake until lightly browned around the edges and a cake tester inserted in the center comes out clean, 30 to 35 minutes. About 5 minutes before the cake is ready, prepare the glaze.

Step 6

Place 2 cups powdered sugar, 2 tablespoons milk, 2 tablespoons honey, and 1 teaspoon vanilla extract in a medium bowl and whisk until smooth. Whisk in up to 1 tablespoon more milk if needed to thin out until pourable.

Step 7

Remove the cake from the oven and place on a wire rack. Immediately pour the glaze over the cake and spread into an even layer with a flexible spatula. Let the cake cool completely, about 1 hour, before cutting into squares and serving.